Merge branch 'v2-prototype' of https://github.com/0xProject/0x-monorepo into feature/website/portal-onboarding-polish

49 files changed, 2599 insertions, 1013 deletions

diff --git a/packages/contracts/src/abstract/abstract_asset_wrapper.ts b/packages/contracts/src/abstract/abstract_asset_wrapper.ts
new file mode 100644
index 000000000..4b56a8502
--- /dev/null
+++ b/packages/contracts/src/abstract/abstract_asset_wrapper.ts
@@ -0,0 +1,3 @@
+export abstract class AbstractAssetWrapper {
+    public abstract getProxyId(): string;
+}
diff --git a/packages/contracts/src/contracts/current/test/DummyERC721Token/DummyERC721Token.sol b/packages/contracts/src/contracts/current/test/DummyERC721Token/DummyERC721Token.sol
index 5503eb2f2..78ea96447 100644
--- a/packages/contracts/src/contracts/current/test/DummyERC721Token/DummyERC721Token.sol
+++ b/packages/contracts/src/contracts/current/test/DummyERC721Token/DummyERC721Token.sol
@@ -56,4 +56,20 @@ contract DummyERC721Token is
         );
         _mint(to, tokenId);
     }
+
+    /**
+    * @dev Function to burn a token
+    * @dev Reverts if the given token ID doesn't exist
+    * @param tokenId uint256 ID of the token to be minted by the msg.sender
+    */
+    function burn(address owner, uint256 tokenId)
+        public
+        onlyOwner
+    {
+        require(
+            exists(tokenId),
+            "Token with tokenId does not exist."
+        );
+        _burn(owner, tokenId);
+    }
 }
diff --git a/packages/contracts/src/utils/asset_wrapper.ts b/packages/contracts/src/utils/asset_wrapper.ts
new file mode 100644
index 000000000..a7f91f413
--- /dev/null
+++ b/packages/contracts/src/utils/asset_wrapper.ts
@@ -0,0 +1,217 @@
+import { assetProxyUtils } from '@0xproject/order-utils';
+import { AssetProxyId } from '@0xproject/types';
+import { BigNumber, errorUtils } from '@0xproject/utils';
+import * as _ from 'lodash';
+
+import { AbstractAssetWrapper } from '../abstract/abstract_asset_wrapper';
+
+import { constants } from './constants';
+import { ERC20Wrapper } from './erc20_wrapper';
+import { ERC721Wrapper } from './erc721_wrapper';
+
+interface ProxyIdToAssetWrappers {
+    [proxyId: string]: AbstractAssetWrapper;
+}
+
+/**
+ * This class abstracts away the differences between ERC20 and ERC721 tokens so that
+ * the logic that uses it does not need to care what standard a token belongs to.
+ */
+export class AssetWrapper {
+    private _proxyIdToAssetWrappers: ProxyIdToAssetWrappers;
+    constructor(assetWrappers: AbstractAssetWrapper[]) {
+        this._proxyIdToAssetWrappers = {};
+        _.each(assetWrappers, assetWrapper => {
+            const proxyId = assetWrapper.getProxyId();
+            this._proxyIdToAssetWrappers[proxyId] = assetWrapper;
+        });
+    }
+    public async getBalanceAsync(userAddress: string, assetData: string): Promise<BigNumber> {
+        const proxyId = assetProxyUtils.decodeAssetDataId(assetData);
+        switch (proxyId) {
+            case AssetProxyId.ERC20: {
+                const erc20Wrapper = this._proxyIdToAssetWrappers[proxyId] as ERC20Wrapper;
+                const balance = await erc20Wrapper.getBalanceAsync(userAddress, assetData);
+                return balance;
+            }
+            case AssetProxyId.ERC721: {
+                const assetWrapper = this._proxyIdToAssetWrappers[proxyId] as ERC721Wrapper;
+                const assetProxyData = assetProxyUtils.decodeERC721AssetData(assetData);
+                const isOwner = await assetWrapper.isOwnerAsync(
+                    userAddress,
+                    assetProxyData.tokenAddress,
+                    assetProxyData.tokenId,
+                );
+                const balance = isOwner ? new BigNumber(1) : new BigNumber(0);
+                return balance;
+            }
+            default:
+                throw errorUtils.spawnSwitchErr('proxyId', proxyId);
+        }
+    }
+    public async setBalanceAsync(userAddress: string, assetData: string, desiredBalance: BigNumber): Promise<void> {
+        const proxyId = assetProxyUtils.decodeAssetDataId(assetData);
+        switch (proxyId) {
+            case AssetProxyId.ERC20: {
+                const erc20Wrapper = this._proxyIdToAssetWrappers[proxyId] as ERC20Wrapper;
+                await erc20Wrapper.setBalanceAsync(userAddress, assetData, desiredBalance);
+                return;
+            }
+            case AssetProxyId.ERC721: {
+                if (!desiredBalance.eq(0) && !desiredBalance.eq(1)) {
+                    throw new Error(`Balance for ERC721 token can only be set to 0 or 1. Got: ${desiredBalance}`);
+                }
+                const erc721Wrapper = this._proxyIdToAssetWrappers[proxyId] as ERC721Wrapper;
+                const assetProxyData = assetProxyUtils.decodeERC721AssetData(assetData);
+                const doesTokenExist = erc721Wrapper.doesTokenExistAsync(
+                    assetProxyData.tokenAddress,
+                    assetProxyData.tokenId,
+                );
+                if (!doesTokenExist && desiredBalance.eq(1)) {
+                    await erc721Wrapper.mintAsync(assetProxyData.tokenAddress, assetProxyData.tokenId, userAddress);
+                    return;
+                } else if (!doesTokenExist && desiredBalance.eq(0)) {
+                    return; // noop
+                }
+                const tokenOwner = await erc721Wrapper.ownerOfAsync(
+                    assetProxyData.tokenAddress,
+                    assetProxyData.tokenId,
+                );
+                if (userAddress !== tokenOwner && desiredBalance.eq(1)) {
+                    await erc721Wrapper.transferFromAsync(
+                        assetProxyData.tokenAddress,
+                        assetProxyData.tokenId,
+                        tokenOwner,
+                        userAddress,
+                    );
+                } else if (tokenOwner === userAddress && desiredBalance.eq(0)) {
+                    // Burn token
+                    await erc721Wrapper.burnAsync(assetProxyData.tokenAddress, assetProxyData.tokenId, userAddress);
+                    return;
+                } else if (
+                    (userAddress !== tokenOwner && desiredBalance.eq(0)) ||
+                    (tokenOwner === userAddress && desiredBalance.eq(1))
+                ) {
+                    return; // noop
+                }
+                break;
+            }
+            default:
+                throw errorUtils.spawnSwitchErr('proxyId', proxyId);
+        }
+    }
+    public async getProxyAllowanceAsync(userAddress: string, assetData: string): Promise<BigNumber> {
+        const proxyId = assetProxyUtils.decodeAssetDataId(assetData);
+        switch (proxyId) {
+            case AssetProxyId.ERC20: {
+                const erc20Wrapper = this._proxyIdToAssetWrappers[proxyId] as ERC20Wrapper;
+                const allowance = await erc20Wrapper.getProxyAllowanceAsync(userAddress, assetData);
+                return allowance;
+            }
+            case AssetProxyId.ERC721: {
+                const assetWrapper = this._proxyIdToAssetWrappers[proxyId] as ERC721Wrapper;
+                const erc721ProxyData = assetProxyUtils.decodeERC721AssetData(assetData);
+                const isProxyApprovedForAll = await assetWrapper.isProxyApprovedForAllAsync(
+                    userAddress,
+                    erc721ProxyData.tokenAddress,
+                );
+                if (isProxyApprovedForAll) {
+                    return constants.UNLIMITED_ALLOWANCE_IN_BASE_UNITS;
+                }
+
+                const isProxyApproved = await assetWrapper.isProxyApprovedAsync(
+                    erc721ProxyData.tokenAddress,
+                    erc721ProxyData.tokenId,
+                );
+                const allowance = isProxyApproved ? new BigNumber(1) : new BigNumber(0);
+                return allowance;
+            }
+            default:
+                throw errorUtils.spawnSwitchErr('proxyId', proxyId);
+        }
+    }
+    public async setProxyAllowanceAsync(
+        userAddress: string,
+        assetData: string,
+        desiredAllowance: BigNumber,
+    ): Promise<void> {
+        const proxyId = assetProxyUtils.decodeAssetDataId(assetData);
+        switch (proxyId) {
+            case AssetProxyId.ERC20: {
+                const erc20Wrapper = this._proxyIdToAssetWrappers[proxyId] as ERC20Wrapper;
+                await erc20Wrapper.setAllowanceAsync(userAddress, assetData, desiredAllowance);
+                return;
+            }
+            case AssetProxyId.ERC721: {
+                if (
+                    !desiredAllowance.eq(0) &&
+                    !desiredAllowance.eq(1) &&
+                    !desiredAllowance.eq(constants.UNLIMITED_ALLOWANCE_IN_BASE_UNITS)
+                ) {
+                    throw new Error(
+                        `Allowance for ERC721 token can only be set to 0, 1 or 2^256-1. Got: ${desiredAllowance}`,
+                    );
+                }
+                const erc721Wrapper = this._proxyIdToAssetWrappers[proxyId] as ERC721Wrapper;
+                const assetProxyData = assetProxyUtils.decodeERC721AssetData(assetData);
+
+                const doesTokenExist = await erc721Wrapper.doesTokenExistAsync(
+                    assetProxyData.tokenAddress,
+                    assetProxyData.tokenId,
+                );
+                if (!doesTokenExist) {
+                    throw new Error(
+                        `Cannot setProxyAllowance on non-existent token: ${assetProxyData.tokenAddress} ${
+                            assetProxyData.tokenId
+                        }`,
+                    );
+                }
+                const isProxyApprovedForAll = await erc721Wrapper.isProxyApprovedForAllAsync(
+                    userAddress,
+                    assetProxyData.tokenAddress,
+                );
+                if (!isProxyApprovedForAll && desiredAllowance.eq(constants.UNLIMITED_ALLOWANCE_IN_BASE_UNITS)) {
+                    const isApproved = true;
+                    await erc721Wrapper.approveProxyForAllAsync(
+                        assetProxyData.tokenAddress,
+                        assetProxyData.tokenId,
+                        isApproved,
+                    );
+                } else if (isProxyApprovedForAll && desiredAllowance.eq(0)) {
+                    const isApproved = false;
+                    await erc721Wrapper.approveProxyForAllAsync(
+                        assetProxyData.tokenAddress,
+                        assetProxyData.tokenId,
+                        isApproved,
+                    );
+                } else if (isProxyApprovedForAll && desiredAllowance.eq(constants.UNLIMITED_ALLOWANCE_IN_BASE_UNITS)) {
+                    return; // Noop
+                }
+
+                const isProxyApproved = await erc721Wrapper.isProxyApprovedAsync(
+                    assetProxyData.tokenAddress,
+                    assetProxyData.tokenId,
+                );
+                if (!isProxyApproved && desiredAllowance.eq(1)) {
+                    await erc721Wrapper.approveProxyAsync(assetProxyData.tokenAddress, assetProxyData.tokenId);
+                } else if (isProxyApproved && desiredAllowance.eq(0)) {
+                    // Remove approval
+                    await erc721Wrapper.approveAsync(
+                        constants.NULL_ADDRESS,
+                        assetProxyData.tokenAddress,
+                        assetProxyData.tokenId,
+                    );
+                } else if (
+                    (!isProxyApproved && desiredAllowance.eq(0)) ||
+                    (isProxyApproved && desiredAllowance.eq(1))
+                ) {
+                    return; // noop
+                }
+
+                break;
+            }
+            default:
+                throw errorUtils.spawnSwitchErr('proxyId', proxyId);
+        }
+    }
+}
diff --git a/packages/contracts/src/utils/core_combinatorial_utils.ts b/packages/contracts/src/utils/core_combinatorial_utils.ts
new file mode 100644
index 000000000..5b725fbe3
--- /dev/null
+++ b/packages/contracts/src/utils/core_combinatorial_utils.ts
@@ -0,0 +1,801 @@
+import {
+    assetProxyUtils,
+    BalanceAndProxyAllowanceLazyStore,
+    ExchangeTransferSimulator,
+    orderHashUtils,
+    OrderStateUtils,
+    OrderValidationUtils,
+} from '@0xproject/order-utils';
+import { AssetProxyId, RevertReason, SignatureType, SignedOrder } from '@0xproject/types';
+import { BigNumber, errorUtils, logUtils } from '@0xproject/utils';
+import { Web3Wrapper } from '@0xproject/web3-wrapper';
+import * as chai from 'chai';
+import { LogWithDecodedArgs, Provider, TxData } from 'ethereum-types';
+import * as _ from 'lodash';
+import 'make-promises-safe';
+
+import { ExchangeContract, FillContractEventArgs } from '../generated_contract_wrappers/exchange';
+import { artifacts } from '../utils/artifacts';
+import { expectRevertReasonOrAlwaysFailingTransactionAsync } from '../utils/assertions';
+import { AssetWrapper } from '../utils/asset_wrapper';
+import { chaiSetup } from '../utils/chai_setup';
+import { constants } from '../utils/constants';
+import { ERC20Wrapper } from '../utils/erc20_wrapper';
+import { ERC721Wrapper } from '../utils/erc721_wrapper';
+import { ExchangeWrapper } from '../utils/exchange_wrapper';
+import { OrderFactoryFromScenario } from '../utils/order_factory_from_scenario';
+import { orderUtils } from '../utils/order_utils';
+import { signingUtils } from '../utils/signing_utils';
+import { SimpleAssetBalanceAndProxyAllowanceFetcher } from '../utils/simple_asset_balance_and_proxy_allowance_fetcher';
+import { SimpleOrderFilledCancelledFetcher } from '../utils/simple_order_filled_cancelled_fetcher';
+import {
+    AllowanceAmountScenario,
+    AssetDataScenario,
+    BalanceAmountScenario,
+    ExpirationTimeSecondsScenario,
+    FeeRecipientAddressScenario,
+    FillScenario,
+    OrderAssetAmountScenario,
+    TakerAssetFillAmountScenario,
+    TakerScenario,
+    TraderStateScenario,
+} from '../utils/types';
+
+chaiSetup.configure();
+const expect = chai.expect;
+
+/**
+ * Instantiates a new instance of CoreCombinatorialUtils. Since this method has some
+ * required async setup, a factory method is required.
+ * @param web3Wrapper Web3Wrapper instance
+ * @param txDefaults Default Ethereum tx options
+ * @return CoreCombinatorialUtils instance
+ */
+export async function coreCombinatorialUtilsFactoryAsync(
+    web3Wrapper: Web3Wrapper,
+    txDefaults: Partial<TxData>,
+): Promise<CoreCombinatorialUtils> {
+    const accounts = await web3Wrapper.getAvailableAddressesAsync();
+    const userAddresses = _.slice(accounts, 0, 5);
+    const [ownerAddress, makerAddress, takerAddress] = userAddresses;
+    const makerPrivateKey = constants.TESTRPC_PRIVATE_KEYS[userAddresses.indexOf(makerAddress)];
+
+    const provider = web3Wrapper.getProvider();
+    const erc20Wrapper = new ERC20Wrapper(provider, userAddresses, ownerAddress);
+    const erc721Wrapper = new ERC721Wrapper(provider, userAddresses, ownerAddress);
+
+    const erc20EighteenDecimalTokenCount = 3;
+    const eighteenDecimals = new BigNumber(18);
+    const [
+        erc20EighteenDecimalTokenA,
+        erc20EighteenDecimalTokenB,
+        zrxToken,
+    ] = await erc20Wrapper.deployDummyTokensAsync(erc20EighteenDecimalTokenCount, eighteenDecimals);
+    const zrxAssetData = assetProxyUtils.encodeERC20AssetData(zrxToken.address);
+
+    const erc20FiveDecimalTokenCount = 2;
+    const fiveDecimals = new BigNumber(18);
+    const [erc20FiveDecimalTokenA, erc20FiveDecimalTokenB] = await erc20Wrapper.deployDummyTokensAsync(
+        erc20FiveDecimalTokenCount,
+        fiveDecimals,
+    );
+    const erc20Proxy = await erc20Wrapper.deployProxyAsync();
+    await erc20Wrapper.setBalancesAndAllowancesAsync();
+
+    const [erc721Token] = await erc721Wrapper.deployDummyTokensAsync();
+    const erc721Proxy = await erc721Wrapper.deployProxyAsync();
+    await erc721Wrapper.setBalancesAndAllowancesAsync();
+    const erc721Balances = await erc721Wrapper.getBalancesAsync();
+
+    const assetWrapper = new AssetWrapper([erc20Wrapper, erc721Wrapper]);
+
+    const exchangeContract = await ExchangeContract.deployFrom0xArtifactAsync(
+        artifacts.Exchange,
+        provider,
+        txDefaults,
+        zrxAssetData,
+    );
+    const exchangeWrapper = new ExchangeWrapper(exchangeContract, provider);
+    await exchangeWrapper.registerAssetProxyAsync(AssetProxyId.ERC20, erc20Proxy.address, ownerAddress);
+    await exchangeWrapper.registerAssetProxyAsync(AssetProxyId.ERC721, erc721Proxy.address, ownerAddress);
+
+    await web3Wrapper.awaitTransactionSuccessAsync(
+        await erc20Proxy.addAuthorizedAddress.sendTransactionAsync(exchangeContract.address, {
+            from: ownerAddress,
+        }),
+        constants.AWAIT_TRANSACTION_MINED_MS,
+    );
+    await web3Wrapper.awaitTransactionSuccessAsync(
+        await erc721Proxy.addAuthorizedAddress.sendTransactionAsync(exchangeContract.address, {
+            from: ownerAddress,
+        }),
+        constants.AWAIT_TRANSACTION_MINED_MS,
+    );
+
+    const orderFactory = new OrderFactoryFromScenario(
+        userAddresses,
+        zrxToken.address,
+        [erc20EighteenDecimalTokenA.address, erc20EighteenDecimalTokenB.address],
+        [erc20FiveDecimalTokenA.address, erc20FiveDecimalTokenB.address],
+        erc721Token,
+        erc721Balances,
+        exchangeContract.address,
+    );
+
+    const coreCombinatorialUtils = new CoreCombinatorialUtils(
+        orderFactory,
+        ownerAddress,
+        makerAddress,
+        makerPrivateKey,
+        takerAddress,
+        zrxAssetData,
+        exchangeWrapper,
+        assetWrapper,
+    );
+    return coreCombinatorialUtils;
+}
+
+export class CoreCombinatorialUtils {
+    public orderFactory: OrderFactoryFromScenario;
+    public ownerAddress: string;
+    public makerAddress: string;
+    public makerPrivateKey: Buffer;
+    public takerAddress: string;
+    public zrxAssetData: string;
+    public exchangeWrapper: ExchangeWrapper;
+    public assetWrapper: AssetWrapper;
+    public static generateFillOrderCombinations(): FillScenario[] {
+        const takerScenarios = [TakerScenario.Unspecified];
+        const feeRecipientScenarios = [FeeRecipientAddressScenario.EthUserAddress];
+        const makerAssetAmountScenario = [OrderAssetAmountScenario.Large];
+        const takerAssetAmountScenario = [OrderAssetAmountScenario.Large];
+        const makerFeeScenario = [OrderAssetAmountScenario.Large];
+        const takerFeeScenario = [OrderAssetAmountScenario.Large];
+        const expirationTimeSecondsScenario = [ExpirationTimeSecondsScenario.InFuture];
+        const makerAssetDataScenario = [
+            AssetDataScenario.ERC20FiveDecimals,
+            AssetDataScenario.ERC20NonZRXEighteenDecimals,
+            AssetDataScenario.ERC721,
+            AssetDataScenario.ZRXFeeToken,
+        ];
+        const takerAssetDataScenario = [
+            AssetDataScenario.ERC20FiveDecimals,
+            AssetDataScenario.ERC20NonZRXEighteenDecimals,
+            AssetDataScenario.ERC721,
+            AssetDataScenario.ZRXFeeToken,
+        ];
+        const takerAssetFillAmountScenario = [TakerAssetFillAmountScenario.ExactlyRemainingFillableTakerAssetAmount];
+        const fillScenarioArrays = CoreCombinatorialUtils._getAllCombinations([
+            takerScenarios,
+            feeRecipientScenarios,
+            makerAssetAmountScenario,
+            takerAssetAmountScenario,
+            makerFeeScenario,
+            takerFeeScenario,
+            expirationTimeSecondsScenario,
+            makerAssetDataScenario,
+            takerAssetDataScenario,
+            takerAssetFillAmountScenario,
+        ]);
+
+        const fillScenarios = _.map(fillScenarioArrays, fillScenarioArray => {
+            const fillScenario: FillScenario = {
+                orderScenario: {
+                    takerScenario: fillScenarioArray[0] as TakerScenario,
+                    feeRecipientScenario: fillScenarioArray[1] as FeeRecipientAddressScenario,
+                    makerAssetAmountScenario: fillScenarioArray[2] as OrderAssetAmountScenario,
+                    takerAssetAmountScenario: fillScenarioArray[3] as OrderAssetAmountScenario,
+                    makerFeeScenario: fillScenarioArray[4] as OrderAssetAmountScenario,
+                    takerFeeScenario: fillScenarioArray[5] as OrderAssetAmountScenario,
+                    expirationTimeSecondsScenario: fillScenarioArray[6] as ExpirationTimeSecondsScenario,
+                    makerAssetDataScenario: fillScenarioArray[7] as AssetDataScenario,
+                    takerAssetDataScenario: fillScenarioArray[8] as AssetDataScenario,
+                },
+                takerAssetFillAmountScenario: fillScenarioArray[9] as TakerAssetFillAmountScenario,
+                makerStateScenario: {
+                    traderAssetBalance: BalanceAmountScenario.Higher,
+                    traderAssetAllowance: AllowanceAmountScenario.Higher,
+                    zrxFeeBalance: BalanceAmountScenario.Higher,
+                    zrxFeeAllowance: AllowanceAmountScenario.Higher,
+                },
+                takerStateScenario: {
+                    traderAssetBalance: BalanceAmountScenario.Higher,
+                    traderAssetAllowance: AllowanceAmountScenario.Higher,
+                    zrxFeeBalance: BalanceAmountScenario.Higher,
+                    zrxFeeAllowance: AllowanceAmountScenario.Higher,
+                },
+            };
+            return fillScenario;
+        });
+
+        return fillScenarios;
+    }
+    /**
+     * Recursive implementation of generating all combinations of the supplied
+     * string-containing arrays.
+     */
+    private static _getAllCombinations(arrays: string[][]): string[][] {
+        // Base case
+        if (arrays.length === 1) {
+            const remainingValues = _.map(arrays[0], val => {
+                return [val];
+            });
+            return remainingValues;
+        } else {
+            const result = [];
+            const restOfArrays = arrays.slice(1);
+            const allCombinationsOfRemaining = CoreCombinatorialUtils._getAllCombinations(restOfArrays); // recur with the rest of array
+            // tslint:disable:prefer-for-of
+            for (let i = 0; i < allCombinationsOfRemaining.length; i++) {
+                for (let j = 0; j < arrays[0].length; j++) {
+                    result.push([arrays[0][j], ...allCombinationsOfRemaining[i]]);
+                }
+            }
+            // tslint:enable:prefer-for-of
+            return result;
+        }
+    }
+    constructor(
+        orderFactory: OrderFactoryFromScenario,
+        ownerAddress: string,
+        makerAddress: string,
+        makerPrivateKey: Buffer,
+        takerAddress: string,
+        zrxAssetData: string,
+        exchangeWrapper: ExchangeWrapper,
+        assetWrapper: AssetWrapper,
+    ) {
+        this.orderFactory = orderFactory;
+        this.ownerAddress = ownerAddress;
+        this.makerAddress = makerAddress;
+        this.makerPrivateKey = makerPrivateKey;
+        this.takerAddress = takerAddress;
+        this.zrxAssetData = zrxAssetData;
+        this.exchangeWrapper = exchangeWrapper;
+        this.assetWrapper = assetWrapper;
+    }
+    public async testFillOrderScenarioAsync(
+        provider: Provider,
+        fillScenario: FillScenario,
+        isVerbose: boolean = false,
+    ): Promise<void> {
+        // 1. Generate order
+        const order = this.orderFactory.generateOrder(fillScenario.orderScenario);
+
+        // 2. Sign order
+        const orderHashBuff = orderHashUtils.getOrderHashBuffer(order);
+        const signature = signingUtils.signMessage(orderHashBuff, this.makerPrivateKey, SignatureType.EthSign);
+        const signedOrder = {
+            ...order,
+            signature: `0x${signature.toString('hex')}`,
+        };
+
+        const balanceAndProxyAllowanceFetcher = new SimpleAssetBalanceAndProxyAllowanceFetcher(this.assetWrapper);
+        const orderFilledCancelledFetcher = new SimpleOrderFilledCancelledFetcher(
+            this.exchangeWrapper,
+            this.zrxAssetData,
+        );
+
+        // 3. Figure out fill amount
+        const takerAssetFillAmount = await this._getTakerAssetFillAmountAsync(
+            signedOrder,
+            fillScenario.takerAssetFillAmountScenario,
+            balanceAndProxyAllowanceFetcher,
+            orderFilledCancelledFetcher,
+        );
+
+        // 4. Permutate the maker and taker balance/allowance scenarios
+        await this._modifyTraderStateAsync(
+            fillScenario.makerStateScenario,
+            fillScenario.takerStateScenario,
+            signedOrder,
+            takerAssetFillAmount,
+        );
+
+        // 5. If I fill it by X, what are the resulting balances/allowances/filled amounts expected?
+        const orderValidationUtils = new OrderValidationUtils(orderFilledCancelledFetcher);
+        const lazyStore = new BalanceAndProxyAllowanceLazyStore(balanceAndProxyAllowanceFetcher);
+        const exchangeTransferSimulator = new ExchangeTransferSimulator(lazyStore);
+
+        let fillRevertReasonIfExists;
+        try {
+            await orderValidationUtils.validateFillOrderThrowIfInvalidAsync(
+                exchangeTransferSimulator,
+                provider,
+                signedOrder,
+                takerAssetFillAmount,
+                this.takerAddress,
+                this.zrxAssetData,
+            );
+            if (isVerbose) {
+                logUtils.log(`Expecting fillOrder to succeed.`);
+            }
+        } catch (err) {
+            fillRevertReasonIfExists = err.message;
+            if (isVerbose) {
+                logUtils.log(`Expecting fillOrder to fail with:`);
+                logUtils.log(err);
+            }
+        }
+
+        // 6. Fill the order
+        await this._fillOrderAndAssertOutcomeAsync(
+            signedOrder,
+            takerAssetFillAmount,
+            lazyStore,
+            fillRevertReasonIfExists,
+        );
+    }
+    private async _fillOrderAndAssertOutcomeAsync(
+        signedOrder: SignedOrder,
+        takerAssetFillAmount: BigNumber,
+        lazyStore: BalanceAndProxyAllowanceLazyStore,
+        fillRevertReasonIfExists: RevertReason | undefined,
+    ): Promise<void> {
+        if (!_.isUndefined(fillRevertReasonIfExists)) {
+            return expectRevertReasonOrAlwaysFailingTransactionAsync(
+                this.exchangeWrapper.fillOrderAsync(signedOrder, this.takerAddress, { takerAssetFillAmount }),
+                fillRevertReasonIfExists,
+            );
+        }
+
+        const makerAddress = signedOrder.makerAddress;
+        const makerAssetData = signedOrder.makerAssetData;
+        const takerAssetData = signedOrder.takerAssetData;
+        const feeRecipient = signedOrder.feeRecipientAddress;
+
+        const expMakerAssetBalanceOfMaker = await lazyStore.getBalanceAsync(makerAssetData, makerAddress);
+        const expMakerAssetAllowanceOfMaker = await lazyStore.getProxyAllowanceAsync(makerAssetData, makerAddress);
+        const expTakerAssetBalanceOfMaker = await lazyStore.getBalanceAsync(takerAssetData, makerAddress);
+        const expZRXAssetBalanceOfMaker = await lazyStore.getBalanceAsync(this.zrxAssetData, makerAddress);
+        const expZRXAssetAllowanceOfMaker = await lazyStore.getProxyAllowanceAsync(this.zrxAssetData, makerAddress);
+        const expTakerAssetBalanceOfTaker = await lazyStore.getBalanceAsync(takerAssetData, this.takerAddress);
+        const expTakerAssetAllowanceOfTaker = await lazyStore.getProxyAllowanceAsync(takerAssetData, this.takerAddress);
+        const expMakerAssetBalanceOfTaker = await lazyStore.getBalanceAsync(makerAssetData, this.takerAddress);
+        const expZRXAssetBalanceOfTaker = await lazyStore.getBalanceAsync(this.zrxAssetData, this.takerAddress);
+        const expZRXAssetAllowanceOfTaker = await lazyStore.getProxyAllowanceAsync(
+            this.zrxAssetData,
+            this.takerAddress,
+        );
+        const expZRXAssetBalanceOfFeeRecipient = await lazyStore.getBalanceAsync(this.zrxAssetData, feeRecipient);
+
+        const orderHash = orderHashUtils.getOrderHashHex(signedOrder);
+        const alreadyFilledTakerAmount = await this.exchangeWrapper.getTakerAssetFilledAmountAsync(orderHash);
+        const remainingTakerAmountToFill = signedOrder.takerAssetAmount.minus(alreadyFilledTakerAmount);
+        const expFilledTakerAmount = takerAssetFillAmount.gt(remainingTakerAmountToFill)
+            ? remainingTakerAmountToFill
+            : alreadyFilledTakerAmount.add(takerAssetFillAmount);
+
+        const expFilledMakerAmount = orderUtils.getPartialAmount(
+            expFilledTakerAmount,
+            signedOrder.takerAssetAmount,
+            signedOrder.makerAssetAmount,
+        );
+
+        // - Let's fill the order!
+        const txReceipt = await this.exchangeWrapper.fillOrderAsync(signedOrder, this.takerAddress, {
+            takerAssetFillAmount,
+        });
+
+        const actFilledTakerAmount = await this.exchangeWrapper.getTakerAssetFilledAmountAsync(orderHash);
+        expect(actFilledTakerAmount).to.be.bignumber.equal(expFilledTakerAmount, 'filledTakerAmount');
+
+        expect(txReceipt.logs.length).to.be.equal(1, 'logs length');
+        // tslint:disable-next-line:no-unnecessary-type-assertion
+        const log = txReceipt.logs[0] as LogWithDecodedArgs<FillContractEventArgs>;
+        expect(log.args.makerAddress).to.be.equal(makerAddress, 'log.args.makerAddress');
+        expect(log.args.takerAddress).to.be.equal(this.takerAddress, 'log.args.this.takerAddress');
+        expect(log.args.feeRecipientAddress).to.be.equal(feeRecipient, 'log.args.feeRecipientAddress');
+        expect(log.args.makerAssetFilledAmount).to.be.bignumber.equal(
+            expFilledMakerAmount,
+            'log.args.makerAssetFilledAmount',
+        );
+        expect(log.args.takerAssetFilledAmount).to.be.bignumber.equal(
+            expFilledTakerAmount,
+            'log.args.takerAssetFilledAmount',
+        );
+        const expMakerFeePaid = orderUtils.getPartialAmount(
+            expFilledTakerAmount,
+            signedOrder.takerAssetAmount,
+            signedOrder.makerFee,
+        );
+        expect(log.args.makerFeePaid).to.be.bignumber.equal(expMakerFeePaid, 'log.args.makerFeePaid');
+        const expTakerFeePaid = orderUtils.getPartialAmount(
+            expFilledTakerAmount,
+            signedOrder.takerAssetAmount,
+            signedOrder.takerFee,
+        );
+        expect(log.args.takerFeePaid).to.be.bignumber.equal(expTakerFeePaid, 'logs.args.takerFeePaid');
+        expect(log.args.orderHash).to.be.equal(orderHash, 'log.args.orderHash');
+        expect(log.args.makerAssetData).to.be.equal(makerAssetData, 'log.args.makerAssetData');
+        expect(log.args.takerAssetData).to.be.equal(takerAssetData, 'log.args.takerAssetData');
+
+        const actMakerAssetBalanceOfMaker = await this.assetWrapper.getBalanceAsync(makerAddress, makerAssetData);
+        expect(actMakerAssetBalanceOfMaker).to.be.bignumber.equal(
+            expMakerAssetBalanceOfMaker,
+            'makerAssetBalanceOfMaker',
+        );
+
+        const actMakerAssetAllowanceOfMaker = await this.assetWrapper.getProxyAllowanceAsync(
+            makerAddress,
+            makerAssetData,
+        );
+        expect(actMakerAssetAllowanceOfMaker).to.be.bignumber.equal(
+            expMakerAssetAllowanceOfMaker,
+            'makerAssetAllowanceOfMaker',
+        );
+
+        const actTakerAssetBalanceOfMaker = await this.assetWrapper.getBalanceAsync(makerAddress, takerAssetData);
+        expect(actTakerAssetBalanceOfMaker).to.be.bignumber.equal(
+            expTakerAssetBalanceOfMaker,
+            'takerAssetBalanceOfMaker',
+        );
+
+        const actZRXAssetBalanceOfMaker = await this.assetWrapper.getBalanceAsync(makerAddress, this.zrxAssetData);
+        expect(actZRXAssetBalanceOfMaker).to.be.bignumber.equal(expZRXAssetBalanceOfMaker, 'ZRXAssetBalanceOfMaker');
+
+        const actZRXAssetAllowanceOfMaker = await this.assetWrapper.getProxyAllowanceAsync(
+            makerAddress,
+            this.zrxAssetData,
+        );
+        expect(actZRXAssetAllowanceOfMaker).to.be.bignumber.equal(
+            expZRXAssetAllowanceOfMaker,
+            'ZRXAssetAllowanceOfMaker',
+        );
+
+        const actTakerAssetBalanceOfTaker = await this.assetWrapper.getBalanceAsync(this.takerAddress, takerAssetData);
+        expect(actTakerAssetBalanceOfTaker).to.be.bignumber.equal(
+            expTakerAssetBalanceOfTaker,
+            'TakerAssetBalanceOfTaker',
+        );
+
+        const actTakerAssetAllowanceOfTaker = await this.assetWrapper.getProxyAllowanceAsync(
+            this.takerAddress,
+            takerAssetData,
+        );
+
+        expect(actTakerAssetAllowanceOfTaker).to.be.bignumber.equal(
+            expTakerAssetAllowanceOfTaker,
+            'TakerAssetAllowanceOfTaker',
+        );
+
+        const actMakerAssetBalanceOfTaker = await this.assetWrapper.getBalanceAsync(this.takerAddress, makerAssetData);
+        expect(actMakerAssetBalanceOfTaker).to.be.bignumber.equal(
+            expMakerAssetBalanceOfTaker,
+            'MakerAssetBalanceOfTaker',
+        );
+
+        const actZRXAssetBalanceOfTaker = await this.assetWrapper.getBalanceAsync(this.takerAddress, this.zrxAssetData);
+        expect(actZRXAssetBalanceOfTaker).to.be.bignumber.equal(expZRXAssetBalanceOfTaker, 'ZRXAssetBalanceOfTaker');
+
+        const actZRXAssetAllowanceOfTaker = await this.assetWrapper.getProxyAllowanceAsync(
+            this.takerAddress,
+            this.zrxAssetData,
+        );
+        expect(actZRXAssetAllowanceOfTaker).to.be.bignumber.equal(
+            expZRXAssetAllowanceOfTaker,
+            'ZRXAssetAllowanceOfTaker',
+        );
+
+        const actZRXAssetBalanceOfFeeRecipient = await this.assetWrapper.getBalanceAsync(
+            feeRecipient,
+            this.zrxAssetData,
+        );
+        expect(actZRXAssetBalanceOfFeeRecipient).to.be.bignumber.equal(
+            expZRXAssetBalanceOfFeeRecipient,
+            'ZRXAssetBalanceOfFeeRecipient',
+        );
+    }
+    private async _getTakerAssetFillAmountAsync(
+        signedOrder: SignedOrder,
+        takerAssetFillAmountScenario: TakerAssetFillAmountScenario,
+        balanceAndProxyAllowanceFetcher: SimpleAssetBalanceAndProxyAllowanceFetcher,
+        orderFilledCancelledFetcher: SimpleOrderFilledCancelledFetcher,
+    ): Promise<BigNumber> {
+        const orderStateUtils = new OrderStateUtils(balanceAndProxyAllowanceFetcher, orderFilledCancelledFetcher);
+        const fillableTakerAssetAmount = await orderStateUtils.getMaxFillableTakerAssetAmountAsync(
+            signedOrder,
+            this.takerAddress,
+        );
+
+        let takerAssetFillAmount;
+        switch (takerAssetFillAmountScenario) {
+            case TakerAssetFillAmountScenario.Zero:
+                takerAssetFillAmount = new BigNumber(0);
+                break;
+
+            case TakerAssetFillAmountScenario.ExactlyRemainingFillableTakerAssetAmount:
+                takerAssetFillAmount = fillableTakerAssetAmount;
+                break;
+
+            case TakerAssetFillAmountScenario.GreaterThanRemainingFillableTakerAssetAmount:
+                takerAssetFillAmount = fillableTakerAssetAmount.add(1);
+                break;
+
+            case TakerAssetFillAmountScenario.LessThanRemainingFillableTakerAssetAmount:
+                const takerAssetProxyId = assetProxyUtils.decodeAssetDataId(signedOrder.takerAssetData);
+                const makerAssetProxyId = assetProxyUtils.decodeAssetDataId(signedOrder.makerAssetData);
+                const isEitherAssetERC721 =
+                    takerAssetProxyId === AssetProxyId.ERC721 || makerAssetProxyId === AssetProxyId.ERC721;
+                if (isEitherAssetERC721) {
+                    throw new Error(
+                        'Cannot test `TakerAssetFillAmountScenario.LessThanRemainingFillableTakerAssetAmount` together with ERC721 assets since orders involving ERC721 must always be filled exactly.',
+                    );
+                }
+                takerAssetFillAmount = fillableTakerAssetAmount.div(2).floor();
+                break;
+
+            default:
+                throw errorUtils.spawnSwitchErr('TakerAssetFillAmountScenario', takerAssetFillAmountScenario);
+        }
+
+        return takerAssetFillAmount;
+    }
+    private async _modifyTraderStateAsync(
+        makerStateScenario: TraderStateScenario,
+        takerStateScenario: TraderStateScenario,
+        signedOrder: SignedOrder,
+        takerAssetFillAmount: BigNumber,
+    ): Promise<void> {
+        const makerAssetFillAmount = orderUtils.getPartialAmount(
+            takerAssetFillAmount,
+            signedOrder.takerAssetAmount,
+            signedOrder.makerAssetAmount,
+        );
+        switch (makerStateScenario.traderAssetBalance) {
+            case BalanceAmountScenario.Higher:
+                break; // Noop since this is already the default
+
+            case BalanceAmountScenario.TooLow:
+                if (makerAssetFillAmount.eq(0)) {
+                    throw new Error(`Cannot set makerAssetBalanceOfMaker TooLow if makerAssetFillAmount is 0`);
+                }
+                const tooLowBalance = makerAssetFillAmount.minus(1);
+                await this.assetWrapper.setBalanceAsync(
+                    signedOrder.makerAddress,
+                    signedOrder.makerAssetData,
+                    tooLowBalance,
+                );
+                break;
+
+            case BalanceAmountScenario.Exact:
+                const exactBalance = makerAssetFillAmount;
+                await this.assetWrapper.setBalanceAsync(
+                    signedOrder.makerAddress,
+                    signedOrder.makerAssetData,
+                    exactBalance,
+                );
+                break;
+
+            default:
+                throw errorUtils.spawnSwitchErr(
+                    'makerStateScenario.traderAssetBalance',
+                    makerStateScenario.traderAssetBalance,
+                );
+        }
+
+        const makerFee = orderUtils.getPartialAmount(
+            takerAssetFillAmount,
+            signedOrder.takerAssetAmount,
+            signedOrder.makerFee,
+        );
+        switch (makerStateScenario.zrxFeeBalance) {
+            case BalanceAmountScenario.Higher:
+                break; // Noop since this is already the default
+
+            case BalanceAmountScenario.TooLow:
+                if (makerFee.eq(0)) {
+                    throw new Error(`Cannot set zrxAsserBalanceOfMaker TooLow if makerFee is 0`);
+                }
+                const tooLowBalance = makerFee.minus(1);
+                await this.assetWrapper.setBalanceAsync(signedOrder.makerAddress, this.zrxAssetData, tooLowBalance);
+                break;
+
+            case BalanceAmountScenario.Exact:
+                const exactBalance = makerFee;
+                await this.assetWrapper.setBalanceAsync(signedOrder.makerAddress, this.zrxAssetData, exactBalance);
+                break;
+
+            default:
+                throw errorUtils.spawnSwitchErr('makerStateScenario.zrxFeeBalance', makerStateScenario.zrxFeeBalance);
+        }
+
+        switch (makerStateScenario.traderAssetAllowance) {
+            case AllowanceAmountScenario.Higher:
+                break; // Noop since this is already the default
+
+            case AllowanceAmountScenario.TooLow:
+                const tooLowAllowance = makerAssetFillAmount.minus(1);
+                await this.assetWrapper.setProxyAllowanceAsync(
+                    signedOrder.makerAddress,
+                    signedOrder.makerAssetData,
+                    tooLowAllowance,
+                );
+                break;
+
+            case AllowanceAmountScenario.Exact:
+                const exactAllowance = makerAssetFillAmount;
+                await this.assetWrapper.setProxyAllowanceAsync(
+                    signedOrder.makerAddress,
+                    signedOrder.makerAssetData,
+                    exactAllowance,
+                );
+                break;
+
+            case AllowanceAmountScenario.Unlimited:
+                await this.assetWrapper.setProxyAllowanceAsync(
+                    signedOrder.makerAddress,
+                    signedOrder.makerAssetData,
+                    constants.UNLIMITED_ALLOWANCE_IN_BASE_UNITS,
+                );
+                break;
+
+            default:
+                throw errorUtils.spawnSwitchErr(
+                    'makerStateScenario.traderAssetAllowance',
+                    makerStateScenario.traderAssetAllowance,
+                );
+        }
+
+        switch (makerStateScenario.zrxFeeAllowance) {
+            case AllowanceAmountScenario.Higher:
+                break; // Noop since this is already the default
+
+            case AllowanceAmountScenario.TooLow:
+                const tooLowAllowance = makerFee.minus(1);
+                await this.assetWrapper.setProxyAllowanceAsync(
+                    signedOrder.makerAddress,
+                    this.zrxAssetData,
+                    tooLowAllowance,
+                );
+                break;
+
+            case AllowanceAmountScenario.Exact:
+                const exactAllowance = makerFee;
+                await this.assetWrapper.setProxyAllowanceAsync(
+                    signedOrder.makerAddress,
+                    this.zrxAssetData,
+                    exactAllowance,
+                );
+                break;
+
+            case AllowanceAmountScenario.Unlimited:
+                await this.assetWrapper.setProxyAllowanceAsync(
+                    signedOrder.makerAddress,
+                    this.zrxAssetData,
+                    constants.UNLIMITED_ALLOWANCE_IN_BASE_UNITS,
+                );
+                break;
+
+            default:
+                throw errorUtils.spawnSwitchErr(
+                    'makerStateScenario.zrxFeeAllowance',
+                    makerStateScenario.zrxFeeAllowance,
+                );
+        }
+
+        switch (takerStateScenario.traderAssetBalance) {
+            case BalanceAmountScenario.Higher:
+                break; // Noop since this is already the default
+
+            case BalanceAmountScenario.TooLow:
+                if (takerAssetFillAmount.eq(0)) {
+                    throw new Error(`Cannot set takerAssetBalanceOfTaker TooLow if takerAssetFillAmount is 0`);
+                }
+                const tooLowBalance = takerAssetFillAmount.minus(1);
+                await this.assetWrapper.setBalanceAsync(this.takerAddress, signedOrder.takerAssetData, tooLowBalance);
+                break;
+
+            case BalanceAmountScenario.Exact:
+                const exactBalance = takerAssetFillAmount;
+                await this.assetWrapper.setBalanceAsync(this.takerAddress, signedOrder.takerAssetData, exactBalance);
+                break;
+
+            default:
+                throw errorUtils.spawnSwitchErr(
+                    'takerStateScenario.traderAssetBalance',
+                    takerStateScenario.traderAssetBalance,
+                );
+        }
+
+        const takerFee = orderUtils.getPartialAmount(
+            takerAssetFillAmount,
+            signedOrder.takerAssetAmount,
+            signedOrder.takerFee,
+        );
+        switch (takerStateScenario.zrxFeeBalance) {
+            case BalanceAmountScenario.Higher:
+                break; // Noop since this is already the default
+
+            case BalanceAmountScenario.TooLow:
+                if (takerFee.eq(0)) {
+                    throw new Error(`Cannot set zrxAssetBalanceOfTaker TooLow if takerFee is 0`);
+                }
+                const tooLowBalance = takerFee.minus(1);
+                await this.assetWrapper.setBalanceAsync(this.takerAddress, this.zrxAssetData, tooLowBalance);
+                break;
+
+            case BalanceAmountScenario.Exact:
+                const exactBalance = takerFee;
+                await this.assetWrapper.setBalanceAsync(this.takerAddress, this.zrxAssetData, exactBalance);
+                break;
+
+            default:
+                throw errorUtils.spawnSwitchErr('takerStateScenario.zrxFeeBalance', takerStateScenario.zrxFeeBalance);
+        }
+
+        switch (takerStateScenario.traderAssetAllowance) {
+            case AllowanceAmountScenario.Higher:
+                break; // Noop since this is already the default
+
+            case AllowanceAmountScenario.TooLow:
+                const tooLowAllowance = takerAssetFillAmount.minus(1);
+                await this.assetWrapper.setProxyAllowanceAsync(
+                    this.takerAddress,
+                    signedOrder.takerAssetData,
+                    tooLowAllowance,
+                );
+                break;
+
+            case AllowanceAmountScenario.Exact:
+                const exactAllowance = takerAssetFillAmount;
+                await this.assetWrapper.setProxyAllowanceAsync(
+                    this.takerAddress,
+                    signedOrder.takerAssetData,
+                    exactAllowance,
+                );
+                break;
+
+            case AllowanceAmountScenario.Unlimited:
+                await this.assetWrapper.setProxyAllowanceAsync(
+                    this.takerAddress,
+                    signedOrder.takerAssetData,
+                    constants.UNLIMITED_ALLOWANCE_IN_BASE_UNITS,
+                );
+                break;
+
+            default:
+                throw errorUtils.spawnSwitchErr(
+                    'takerStateScenario.traderAssetAllowance',
+                    takerStateScenario.traderAssetAllowance,
+                );
+        }
+
+        switch (takerStateScenario.zrxFeeAllowance) {
+            case AllowanceAmountScenario.Higher:
+                break; // Noop since this is already the default
+
+            case AllowanceAmountScenario.TooLow:
+                const tooLowAllowance = takerFee.minus(1);
+                await this.assetWrapper.setProxyAllowanceAsync(
+                    signedOrder.takerAddress,
+                    this.zrxAssetData,
+                    tooLowAllowance,
+                );
+                break;
+
+            case AllowanceAmountScenario.Exact:
+                const exactAllowance = takerFee;
+                await this.assetWrapper.setProxyAllowanceAsync(
+                    signedOrder.takerAddress,
+                    this.zrxAssetData,
+                    exactAllowance,
+                );
+                break;
+
+            case AllowanceAmountScenario.Unlimited:
+                await this.assetWrapper.setProxyAllowanceAsync(
+                    signedOrder.takerAddress,
+                    this.zrxAssetData,
+                    constants.UNLIMITED_ALLOWANCE_IN_BASE_UNITS,
+                );
+                break;
+
+            default:
+                throw errorUtils.spawnSwitchErr(
+                    'takerStateScenario.zrxFeeAllowance',
+                    takerStateScenario.zrxFeeAllowance,
+                );
+        }
+    }
+} // tslint:disable:max-file-line-count
diff --git a/packages/contracts/src/utils/erc20_wrapper.ts b/packages/contracts/src/utils/erc20_wrapper.ts
index 91c9d50b7..7f00e2061 100644
--- a/packages/contracts/src/utils/erc20_wrapper.ts
+++ b/packages/contracts/src/utils/erc20_wrapper.ts
@@ -1,3 +1,4 @@
+import { assetProxyUtils } from '@0xproject/order-utils';
 import { BigNumber } from '@0xproject/utils';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import { Provider } from 'ethereum-types';
@@ -18,6 +19,7 @@ export class ERC20Wrapper {
     private _provider: Provider;
     private _dummyTokenContracts: DummyERC20TokenContract[];
     private _proxyContract?: ERC20ProxyContract;
+    private _proxyIdIfExists?: string;
     constructor(provider: Provider, tokenOwnerAddresses: string[], contractOwnerAddress: string) {
         this._dummyTokenContracts = [];
         this._web3Wrapper = new Web3Wrapper(provider);
@@ -25,8 +27,11 @@ export class ERC20Wrapper {
         this._tokenOwnerAddresses = tokenOwnerAddresses;
         this._contractOwnerAddress = contractOwnerAddress;
     }
-    public async deployDummyTokensAsync(): Promise<DummyERC20TokenContract[]> {
-        for (let i = 0; i < constants.NUM_DUMMY_ERC20_TO_DEPLOY; i++) {
+    public async deployDummyTokensAsync(
+        numberToDeploy: number,
+        decimals: BigNumber,
+    ): Promise<DummyERC20TokenContract[]> {
+        for (let i = 0; i < numberToDeploy; i++) {
             this._dummyTokenContracts.push(
                 await DummyERC20TokenContract.deployFrom0xArtifactAsync(
                     artifacts.DummyERC20Token,
@@ -34,7 +39,7 @@ export class ERC20Wrapper {
                     txDefaults,
                     constants.DUMMY_TOKEN_NAME,
                     constants.DUMMY_TOKEN_SYMBOL,
-                    constants.DUMMY_TOKEN_DECIMALS,
+                    decimals,
                     constants.DUMMY_TOKEN_TOTAL_SUPPLY,
                 ),
             );
@@ -47,8 +52,13 @@ export class ERC20Wrapper {
             this._provider,
             txDefaults,
         );
+        this._proxyIdIfExists = await this._proxyContract.getProxyId.callAsync();
         return this._proxyContract;
     }
+    public getProxyId(): string {
+        this._validateProxyContractExistsOrThrow();
+        return this._proxyIdIfExists as string;
+    }
     public async setBalancesAndAllowancesAsync(): Promise<void> {
         this._validateDummyTokenContractsExistOrThrow();
         this._validateProxyContractExistsOrThrow();
@@ -73,6 +83,36 @@ export class ERC20Wrapper {
             }
         }
     }
+    public async getBalanceAsync(userAddress: string, assetData: string): Promise<BigNumber> {
+        const tokenContract = this._getTokenContractFromAssetData(assetData);
+        const balance = new BigNumber(await tokenContract.balanceOf.callAsync(userAddress));
+        return balance;
+    }
+    public async setBalanceAsync(userAddress: string, assetData: string, amount: BigNumber): Promise<void> {
+        const tokenContract = this._getTokenContractFromAssetData(assetData);
+        await this._web3Wrapper.awaitTransactionSuccessAsync(
+            await tokenContract.setBalance.sendTransactionAsync(userAddress, amount, {
+                from: this._contractOwnerAddress,
+            }),
+            constants.AWAIT_TRANSACTION_MINED_MS,
+        );
+    }
+    public async getProxyAllowanceAsync(userAddress: string, assetData: string): Promise<BigNumber> {
+        const tokenContract = this._getTokenContractFromAssetData(assetData);
+        const proxyAddress = (this._proxyContract as ERC20ProxyContract).address;
+        const allowance = new BigNumber(await tokenContract.allowance.callAsync(userAddress, proxyAddress));
+        return allowance;
+    }
+    public async setAllowanceAsync(userAddress: string, assetData: string, amount: BigNumber): Promise<void> {
+        const tokenContract = this._getTokenContractFromAssetData(assetData);
+        const proxyAddress = (this._proxyContract as ERC20ProxyContract).address;
+        await this._web3Wrapper.awaitTransactionSuccessAsync(
+            await tokenContract.approve.sendTransactionAsync(proxyAddress, amount, {
+                from: userAddress,
+            }),
+            constants.AWAIT_TRANSACTION_MINED_MS,
+        );
+    }
     public async getBalancesAsync(): Promise<ERC20BalancesByOwner> {
         this._validateDummyTokenContractsExistOrThrow();
         const balancesByOwner: ERC20BalancesByOwner = {};
@@ -105,6 +145,15 @@ export class ERC20Wrapper {
         const tokenAddresses = _.map(this._dummyTokenContracts, dummyTokenContract => dummyTokenContract.address);
         return tokenAddresses;
     }
+    private _getTokenContractFromAssetData(assetData: string): DummyERC20TokenContract {
+        const erc20ProxyData = assetProxyUtils.decodeERC20AssetData(assetData);
+        const tokenAddress = erc20ProxyData.tokenAddress;
+        const tokenContractIfExists = _.find(this._dummyTokenContracts, c => c.address === tokenAddress);
+        if (_.isUndefined(tokenContractIfExists)) {
+            throw new Error(`Token: ${tokenAddress} was not deployed through ERC20Wrapper`);
+        }
+        return tokenContractIfExists;
+    }
     private _validateDummyTokenContractsExistOrThrow(): void {
         if (_.isUndefined(this._dummyTokenContracts)) {
             throw new Error('Dummy ERC20 tokens not yet deployed, please call "deployDummyTokensAsync"');
diff --git a/packages/contracts/src/utils/erc721_wrapper.ts b/packages/contracts/src/utils/erc721_wrapper.ts
index b20d9acd2..309135ae4 100644
--- a/packages/contracts/src/utils/erc721_wrapper.ts
+++ b/packages/contracts/src/utils/erc721_wrapper.ts
@@ -19,6 +19,7 @@ export class ERC721Wrapper {
     private _provider: Provider;
     private _dummyTokenContracts: DummyERC721TokenContract[];
     private _proxyContract?: ERC721ProxyContract;
+    private _proxyIdIfExists?: string;
     private _initialTokenIdsByOwner: ERC721TokenIdsByOwner = {};
     constructor(provider: Provider, tokenOwnerAddresses: string[], contractOwnerAddress: string) {
         this._web3Wrapper = new Web3Wrapper(provider);
@@ -47,8 +48,13 @@ export class ERC721Wrapper {
             this._provider,
             txDefaults,
         );
+        this._proxyIdIfExists = await this._proxyContract.getProxyId.callAsync();
         return this._proxyContract;
     }
+    public getProxyId(): string {
+        this._validateProxyContractExistsOrThrow();
+        return this._proxyIdIfExists as string;
+    }
     public async setBalancesAndAllowancesAsync(): Promise<void> {
         this._validateDummyTokenContractsExistOrThrow();
         this._validateProxyContractExistsOrThrow();
@@ -57,12 +63,7 @@ export class ERC721Wrapper {
             for (const tokenOwnerAddress of this._tokenOwnerAddresses) {
                 for (let i = 0; i < constants.NUM_ERC721_TOKENS_TO_MINT; i++) {
                     const tokenId = generatePseudoRandomSalt();
-                    await this._web3Wrapper.awaitTransactionSuccessAsync(
-                        await dummyTokenContract.mint.sendTransactionAsync(tokenOwnerAddress, tokenId, {
-                            from: this._contractOwnerAddress,
-                        }),
-                        constants.AWAIT_TRANSACTION_MINED_MS,
-                    );
+                    await this.mintAsync(dummyTokenContract.address, tokenId, tokenOwnerAddress);
                     if (_.isUndefined(this._initialTokenIdsByOwner[tokenOwnerAddress])) {
                         this._initialTokenIdsByOwner[tokenOwnerAddress] = {
                             [dummyTokenContract.address]: [],
@@ -72,19 +73,100 @@ export class ERC721Wrapper {
                         this._initialTokenIdsByOwner[tokenOwnerAddress][dummyTokenContract.address] = [];
                     }
                     this._initialTokenIdsByOwner[tokenOwnerAddress][dummyTokenContract.address].push(tokenId);
+
+                    await this.approveProxyAsync(dummyTokenContract.address, tokenId);
                 }
-                const shouldApprove = true;
-                await this._web3Wrapper.awaitTransactionSuccessAsync(
-                    await dummyTokenContract.setApprovalForAll.sendTransactionAsync(
-                        (this._proxyContract as ERC721ProxyContract).address,
-                        shouldApprove,
-                        { from: tokenOwnerAddress },
-                    ),
-                    constants.AWAIT_TRANSACTION_MINED_MS,
-                );
             }
         }
     }
+    public async doesTokenExistAsync(tokenAddress: string, tokenId: BigNumber): Promise<boolean> {
+        const tokenContract = this._getTokenContractFromAssetData(tokenAddress);
+        const doesExist = await tokenContract.exists.callAsync(tokenId);
+        return doesExist;
+    }
+    public async approveProxyAsync(tokenAddress: string, tokenId: BigNumber): Promise<void> {
+        const proxyAddress = (this._proxyContract as ERC721ProxyContract).address;
+        await this.approveAsync(proxyAddress, tokenAddress, tokenId);
+    }
+    public async approveProxyForAllAsync(tokenAddress: string, tokenId: BigNumber, isApproved: boolean): Promise<void> {
+        const tokenContract = this._getTokenContractFromAssetData(tokenAddress);
+        const tokenOwner = await this.ownerOfAsync(tokenAddress, tokenId);
+        const proxyAddress = (this._proxyContract as ERC721ProxyContract).address;
+        await this._web3Wrapper.awaitTransactionSuccessAsync(
+            await tokenContract.setApprovalForAll.sendTransactionAsync(proxyAddress, isApproved, {
+                from: tokenOwner,
+            }),
+            constants.AWAIT_TRANSACTION_MINED_MS,
+        );
+    }
+    public async approveAsync(to: string, tokenAddress: string, tokenId: BigNumber): Promise<void> {
+        const tokenContract = this._getTokenContractFromAssetData(tokenAddress);
+        const tokenOwner = await this.ownerOfAsync(tokenAddress, tokenId);
+        await this._web3Wrapper.awaitTransactionSuccessAsync(
+            await tokenContract.approve.sendTransactionAsync(to, tokenId, {
+                from: tokenOwner,
+            }),
+            constants.AWAIT_TRANSACTION_MINED_MS,
+        );
+    }
+    public async transferFromAsync(
+        tokenAddress: string,
+        tokenId: BigNumber,
+        currentOwner: string,
+        userAddress: string,
+    ): Promise<void> {
+        const tokenContract = this._getTokenContractFromAssetData(tokenAddress);
+        await this._web3Wrapper.awaitTransactionSuccessAsync(
+            await tokenContract.transferFrom.sendTransactionAsync(currentOwner, userAddress, tokenId, {
+                from: currentOwner,
+            }),
+            constants.AWAIT_TRANSACTION_MINED_MS,
+        );
+    }
+    public async mintAsync(tokenAddress: string, tokenId: BigNumber, userAddress: string): Promise<void> {
+        const tokenContract = this._getTokenContractFromAssetData(tokenAddress);
+        await this._web3Wrapper.awaitTransactionSuccessAsync(
+            await tokenContract.mint.sendTransactionAsync(userAddress, tokenId, {
+                from: this._contractOwnerAddress,
+            }),
+            constants.AWAIT_TRANSACTION_MINED_MS,
+        );
+    }
+    public async burnAsync(tokenAddress: string, tokenId: BigNumber, owner: string): Promise<void> {
+        const tokenContract = this._getTokenContractFromAssetData(tokenAddress);
+        await this._web3Wrapper.awaitTransactionSuccessAsync(
+            await tokenContract.burn.sendTransactionAsync(owner, tokenId, {
+                from: this._contractOwnerAddress,
+            }),
+            constants.AWAIT_TRANSACTION_MINED_MS,
+        );
+    }
+    public async ownerOfAsync(tokenAddress: string, tokenId: BigNumber): Promise<string> {
+        const tokenContract = this._getTokenContractFromAssetData(tokenAddress);
+        const owner = await tokenContract.ownerOf.callAsync(tokenId);
+        return owner;
+    }
+    public async isOwnerAsync(userAddress: string, tokenAddress: string, tokenId: BigNumber): Promise<boolean> {
+        const tokenContract = this._getTokenContractFromAssetData(tokenAddress);
+        const tokenOwner = await tokenContract.ownerOf.callAsync(tokenId);
+        const isOwner = tokenOwner === userAddress;
+        return isOwner;
+    }
+    public async isProxyApprovedForAllAsync(userAddress: string, tokenAddress: string): Promise<boolean> {
+        this._validateProxyContractExistsOrThrow();
+        const tokenContract = this._getTokenContractFromAssetData(tokenAddress);
+        const operator = (this._proxyContract as ERC721ProxyContract).address;
+        const didApproveAll = await tokenContract.isApprovedForAll.callAsync(userAddress, operator);
+        return didApproveAll;
+    }
+    public async isProxyApprovedAsync(tokenAddress: string, tokenId: BigNumber): Promise<boolean> {
+        this._validateProxyContractExistsOrThrow();
+        const tokenContract = this._getTokenContractFromAssetData(tokenAddress);
+        const approvedAddress = await tokenContract.getApproved.callAsync(tokenId);
+        const proxyAddress = (this._proxyContract as ERC721ProxyContract).address;
+        const isProxyAnApprovedOperator = approvedAddress === proxyAddress;
+        return isProxyAnApprovedOperator;
+    }
     public async getBalancesAsync(): Promise<ERC721TokenIdsByOwner> {
         this._validateDummyTokenContractsExistOrThrow();
         this._validateBalancesAndAllowancesSetOrThrow();
@@ -127,6 +209,13 @@ export class ERC721Wrapper {
         const tokenAddresses = _.map(this._dummyTokenContracts, dummyTokenContract => dummyTokenContract.address);
         return tokenAddresses;
     }
+    private _getTokenContractFromAssetData(tokenAddress: string): DummyERC721TokenContract {
+        const tokenContractIfExists = _.find(this._dummyTokenContracts, c => c.address === tokenAddress);
+        if (_.isUndefined(tokenContractIfExists)) {
+            throw new Error(`Token: ${tokenAddress} was not deployed through ERC20Wrapper`);
+        }
+        return tokenContractIfExists;
+    }
     private _validateDummyTokenContractsExistOrThrow(): void {
         if (_.isUndefined(this._dummyTokenContracts)) {
             throw new Error('Dummy ERC721 tokens not yet deployed, please call "deployDummyTokensAsync"');
diff --git a/packages/contracts/src/utils/exchange_wrapper.ts b/packages/contracts/src/utils/exchange_wrapper.ts
index 06eb70644..ad68c8ff4 100644
--- a/packages/contracts/src/utils/exchange_wrapper.ts
+++ b/packages/contracts/src/utils/exchange_wrapper.ts
@@ -33,8 +33,8 @@ export class ExchangeWrapper {
             params.signature,
             { from },
         );
-        const tx = await this._logDecoder.getTxWithDecodedLogsAsync(txHash);
-        return tx;
+        const txReceipt = await this._logDecoder.getTxWithDecodedLogsAsync(txHash);
+        return txReceipt;
     }
     public async cancelOrderAsync(signedOrder: SignedOrder, from: string): Promise<TransactionReceiptWithDecodedLogs> {
         const params = orderUtils.createCancel(signedOrder);
@@ -227,6 +227,10 @@ export class ExchangeWrapper {
         const filledAmount = new BigNumber(await this._exchange.filled.callAsync(orderHashHex));
         return filledAmount;
     }
+    public async isCancelledAsync(orderHashHex: string): Promise<boolean> {
+        const isCancelled = await this._exchange.cancelled.callAsync(orderHashHex);
+        return isCancelled;
+    }
     public async getOrderInfoAsync(signedOrder: SignedOrder): Promise<OrderInfo> {
         const orderInfo = (await this._exchange.getOrderInfo.callAsync(signedOrder)) as OrderInfo;
         return orderInfo;
diff --git a/packages/contracts/src/utils/order_factory_from_scenario.ts b/packages/contracts/src/utils/order_factory_from_scenario.ts
new file mode 100644
index 000000000..b150e59f6
--- /dev/null
+++ b/packages/contracts/src/utils/order_factory_from_scenario.ts
@@ -0,0 +1,277 @@
+import { assetProxyUtils, generatePseudoRandomSalt } from '@0xproject/order-utils';
+import { Order } from '@0xproject/types';
+import { BigNumber, errorUtils } from '@0xproject/utils';
+
+import { DummyERC721TokenContract } from '../generated_contract_wrappers/dummy_e_r_c721_token';
+
+import { constants } from './constants';
+import {
+    AssetDataScenario,
+    ERC721TokenIdsByOwner,
+    ExpirationTimeSecondsScenario,
+    FeeRecipientAddressScenario,
+    OrderAssetAmountScenario,
+    OrderScenario,
+    TakerScenario,
+} from './types';
+
+const TEN_UNITS_EIGHTEEN_DECIMALS = new BigNumber(10_000_000_000_000_000_000);
+const FIVE_UNITS_EIGHTEEN_DECIMALS = new BigNumber(5_000_000_000_000_000_000);
+const POINT_ONE_UNITS_EIGHTEEN_DECIMALS = new BigNumber(100_000_000_000_000_000);
+const POINT_ZERO_FIVE_UNITS_EIGHTEEN_DECIMALS = new BigNumber(50_000_000_000_000_000);
+const TEN_UNITS_FIVE_DECIMALS = new BigNumber(1_000_000);
+const FIVE_UNITS_FIVE_DECIMALS = new BigNumber(500_000);
+const ONE_NFT_UNIT = new BigNumber(1);
+
+export class OrderFactoryFromScenario {
+    private _userAddresses: string[];
+    private _zrxAddress: string;
+    private _nonZrxERC20EighteenDecimalTokenAddresses: string[];
+    private _erc20FiveDecimalTokenAddresses: string[];
+    private _erc721Token: DummyERC721TokenContract;
+    private _erc721Balances: ERC721TokenIdsByOwner;
+    private _exchangeAddress: string;
+    constructor(
+        userAddresses: string[],
+        zrxAddress: string,
+        nonZrxERC20EighteenDecimalTokenAddresses: string[],
+        erc20FiveDecimalTokenAddresses: string[],
+        erc721Token: DummyERC721TokenContract,
+        erc721Balances: ERC721TokenIdsByOwner,
+        exchangeAddress: string,
+    ) {
+        this._userAddresses = userAddresses;
+        this._zrxAddress = zrxAddress;
+        this._nonZrxERC20EighteenDecimalTokenAddresses = nonZrxERC20EighteenDecimalTokenAddresses;
+        this._erc20FiveDecimalTokenAddresses = erc20FiveDecimalTokenAddresses;
+        this._erc721Token = erc721Token;
+        this._erc721Balances = erc721Balances;
+        this._exchangeAddress = exchangeAddress;
+    }
+    public generateOrder(orderScenario: OrderScenario): Order {
+        const makerAddress = this._userAddresses[1];
+        let takerAddress = this._userAddresses[2];
+        const erc721MakerAssetIds = this._erc721Balances[makerAddress][this._erc721Token.address];
+        const erc721TakerAssetIds = this._erc721Balances[takerAddress][this._erc721Token.address];
+        let feeRecipientAddress;
+        let makerAssetAmount;
+        let takerAssetAmount;
+        let makerFee;
+        let takerFee;
+        let expirationTimeSeconds;
+        let makerAssetData;
+        let takerAssetData;
+
+        switch (orderScenario.feeRecipientScenario) {
+            case FeeRecipientAddressScenario.BurnAddress:
+                feeRecipientAddress = constants.NULL_ADDRESS;
+                break;
+            case FeeRecipientAddressScenario.EthUserAddress:
+                feeRecipientAddress = this._userAddresses[4];
+                break;
+            default:
+                throw errorUtils.spawnSwitchErr('FeeRecipientAddressScenario', orderScenario.feeRecipientScenario);
+        }
+
+        switch (orderScenario.makerAssetDataScenario) {
+            case AssetDataScenario.ZRXFeeToken:
+                makerAssetData = assetProxyUtils.encodeERC20AssetData(this._zrxAddress);
+                break;
+            case AssetDataScenario.ERC20NonZRXEighteenDecimals:
+                makerAssetData = assetProxyUtils.encodeERC20AssetData(
+                    this._nonZrxERC20EighteenDecimalTokenAddresses[0],
+                );
+                break;
+            case AssetDataScenario.ERC20FiveDecimals:
+                makerAssetData = assetProxyUtils.encodeERC20AssetData(this._erc20FiveDecimalTokenAddresses[0]);
+                break;
+            case AssetDataScenario.ERC721:
+                makerAssetData = assetProxyUtils.encodeERC721AssetData(
+                    this._erc721Token.address,
+                    erc721MakerAssetIds[0],
+                );
+                break;
+            default:
+                throw errorUtils.spawnSwitchErr('AssetDataScenario', orderScenario.makerAssetDataScenario);
+        }
+
+        switch (orderScenario.takerAssetDataScenario) {
+            case AssetDataScenario.ZRXFeeToken:
+                takerAssetData = assetProxyUtils.encodeERC20AssetData(this._zrxAddress);
+                break;
+            case AssetDataScenario.ERC20NonZRXEighteenDecimals:
+                takerAssetData = assetProxyUtils.encodeERC20AssetData(
+                    this._nonZrxERC20EighteenDecimalTokenAddresses[1],
+                );
+                break;
+            case AssetDataScenario.ERC20FiveDecimals:
+                takerAssetData = assetProxyUtils.encodeERC20AssetData(this._erc20FiveDecimalTokenAddresses[1]);
+                break;
+            case AssetDataScenario.ERC721:
+                takerAssetData = assetProxyUtils.encodeERC721AssetData(
+                    this._erc721Token.address,
+                    erc721TakerAssetIds[0],
+                );
+                break;
+            default:
+                throw errorUtils.spawnSwitchErr('AssetDataScenario', orderScenario.takerAssetDataScenario);
+        }
+
+        switch (orderScenario.makerAssetAmountScenario) {
+            case OrderAssetAmountScenario.Large:
+                switch (orderScenario.makerAssetDataScenario) {
+                    case AssetDataScenario.ZRXFeeToken:
+                    case AssetDataScenario.ERC20NonZRXEighteenDecimals:
+                        makerAssetAmount = TEN_UNITS_EIGHTEEN_DECIMALS;
+                        break;
+                    case AssetDataScenario.ERC20FiveDecimals:
+                        makerAssetAmount = TEN_UNITS_FIVE_DECIMALS;
+                        break;
+                    case AssetDataScenario.ERC721:
+                        makerAssetAmount = ONE_NFT_UNIT;
+                        break;
+                    default:
+                        throw errorUtils.spawnSwitchErr('AssetDataScenario', orderScenario.makerAssetDataScenario);
+                }
+                break;
+            case OrderAssetAmountScenario.Small:
+                switch (orderScenario.makerAssetDataScenario) {
+                    case AssetDataScenario.ZRXFeeToken:
+                    case AssetDataScenario.ERC20NonZRXEighteenDecimals:
+                        makerAssetAmount = FIVE_UNITS_EIGHTEEN_DECIMALS;
+                        break;
+                    case AssetDataScenario.ERC20FiveDecimals:
+                        makerAssetAmount = FIVE_UNITS_FIVE_DECIMALS;
+                        break;
+                    case AssetDataScenario.ERC721:
+                        makerAssetAmount = ONE_NFT_UNIT;
+                        break;
+                    default:
+                        throw errorUtils.spawnSwitchErr('AssetDataScenario', orderScenario.makerAssetDataScenario);
+                }
+                break;
+            case OrderAssetAmountScenario.Zero:
+                makerAssetAmount = new BigNumber(0);
+                break;
+            default:
+                throw errorUtils.spawnSwitchErr('OrderAssetAmountScenario', orderScenario.makerAssetAmountScenario);
+        }
+
+        switch (orderScenario.takerAssetAmountScenario) {
+            case OrderAssetAmountScenario.Large:
+                switch (orderScenario.takerAssetDataScenario) {
+                    case AssetDataScenario.ERC20NonZRXEighteenDecimals:
+                    case AssetDataScenario.ZRXFeeToken:
+                        takerAssetAmount = TEN_UNITS_EIGHTEEN_DECIMALS;
+                        break;
+                    case AssetDataScenario.ERC20FiveDecimals:
+                        takerAssetAmount = TEN_UNITS_FIVE_DECIMALS;
+                        break;
+                    case AssetDataScenario.ERC721:
+                        takerAssetAmount = ONE_NFT_UNIT;
+                        break;
+                    default:
+                        throw errorUtils.spawnSwitchErr('AssetDataScenario', orderScenario.takerAssetDataScenario);
+                }
+                break;
+            case OrderAssetAmountScenario.Small:
+                switch (orderScenario.takerAssetDataScenario) {
+                    case AssetDataScenario.ERC20NonZRXEighteenDecimals:
+                    case AssetDataScenario.ZRXFeeToken:
+                        takerAssetAmount = FIVE_UNITS_EIGHTEEN_DECIMALS;
+                        break;
+                    case AssetDataScenario.ERC20FiveDecimals:
+                        takerAssetAmount = FIVE_UNITS_FIVE_DECIMALS;
+                        break;
+                    case AssetDataScenario.ERC721:
+                        takerAssetAmount = ONE_NFT_UNIT;
+                        break;
+                    default:
+                        throw errorUtils.spawnSwitchErr('AssetDataScenario', orderScenario.takerAssetDataScenario);
+                }
+                break;
+            case OrderAssetAmountScenario.Zero:
+                takerAssetAmount = new BigNumber(0);
+                break;
+            default:
+                throw errorUtils.spawnSwitchErr('OrderAssetAmountScenario', orderScenario.takerAssetAmountScenario);
+        }
+
+        switch (orderScenario.makerFeeScenario) {
+            case OrderAssetAmountScenario.Large:
+                makerFee = POINT_ONE_UNITS_EIGHTEEN_DECIMALS;
+                break;
+            case OrderAssetAmountScenario.Small:
+                makerFee = POINT_ZERO_FIVE_UNITS_EIGHTEEN_DECIMALS;
+                break;
+            case OrderAssetAmountScenario.Zero:
+                makerFee = new BigNumber(0);
+                break;
+            default:
+                throw errorUtils.spawnSwitchErr('OrderAssetAmountScenario', orderScenario.makerFeeScenario);
+        }
+
+        switch (orderScenario.takerFeeScenario) {
+            case OrderAssetAmountScenario.Large:
+                takerFee = POINT_ONE_UNITS_EIGHTEEN_DECIMALS;
+                break;
+            case OrderAssetAmountScenario.Small:
+                takerFee = POINT_ZERO_FIVE_UNITS_EIGHTEEN_DECIMALS;
+                break;
+            case OrderAssetAmountScenario.Zero:
+                takerFee = new BigNumber(0);
+                break;
+            default:
+                throw errorUtils.spawnSwitchErr('OrderAssetAmountScenario', orderScenario.takerFeeScenario);
+        }
+
+        switch (orderScenario.expirationTimeSecondsScenario) {
+            case ExpirationTimeSecondsScenario.InFuture:
+                expirationTimeSeconds = new BigNumber(2524604400); // Close to infinite
+                break;
+            case ExpirationTimeSecondsScenario.InPast:
+                expirationTimeSeconds = new BigNumber(0); // Jan 1, 1970
+                break;
+            default:
+                throw errorUtils.spawnSwitchErr(
+                    'ExpirationTimeSecondsScenario',
+                    orderScenario.expirationTimeSecondsScenario,
+                );
+        }
+
+        switch (orderScenario.takerScenario) {
+            case TakerScenario.CorrectlySpecified:
+                break; // noop since takerAddress is already specified
+
+            case TakerScenario.IncorrectlySpecified:
+                const notTaker = this._userAddresses[3];
+                takerAddress = notTaker;
+                break;
+
+            case TakerScenario.Unspecified:
+                takerAddress = constants.NULL_ADDRESS;
+                break;
+
+            default:
+                throw errorUtils.spawnSwitchErr('TakerScenario', orderScenario.takerScenario);
+        }
+
+        const order = {
+            senderAddress: constants.NULL_ADDRESS,
+            makerAddress,
+            takerAddress,
+            makerFee,
+            takerFee,
+            makerAssetAmount,
+            takerAssetAmount,
+            makerAssetData,
+            takerAssetData,
+            salt: generatePseudoRandomSalt(),
+            exchangeAddress: this._exchangeAddress,
+            feeRecipientAddress,
+            expirationTimeSeconds,
+        };
+
+        return order;
+    }
+}
diff --git a/packages/contracts/src/utils/order_utils.ts b/packages/contracts/src/utils/order_utils.ts
index a9f994d80..019f6e74b 100644
--- a/packages/contracts/src/utils/order_utils.ts
+++ b/packages/contracts/src/utils/order_utils.ts
@@ -5,6 +5,13 @@ import { constants } from './constants';
 import { CancelOrder, MatchOrder } from './types';
 
 export const orderUtils = {
+    getPartialAmount(numerator: BigNumber, denominator: BigNumber, target: BigNumber): BigNumber {
+        const partialAmount = numerator
+            .mul(target)
+            .div(denominator)
+            .floor();
+        return partialAmount;
+    },
     createFill: (signedOrder: SignedOrder, takerAssetFillAmount?: BigNumber) => {
         const fill = {
             order: orderUtils.getOrderWithoutExchangeAddress(signedOrder),
diff --git a/packages/contracts/src/utils/simple_asset_balance_and_proxy_allowance_fetcher.ts b/packages/contracts/src/utils/simple_asset_balance_and_proxy_allowance_fetcher.ts
new file mode 100644
index 000000000..a295a40c4
--- /dev/null
+++ b/packages/contracts/src/utils/simple_asset_balance_and_proxy_allowance_fetcher.ts
@@ -0,0 +1,19 @@
+import { AbstractBalanceAndProxyAllowanceFetcher } from '@0xproject/order-utils';
+import { BigNumber } from '@0xproject/utils';
+
+import { AssetWrapper } from './asset_wrapper';
+
+export class SimpleAssetBalanceAndProxyAllowanceFetcher implements AbstractBalanceAndProxyAllowanceFetcher {
+    private _assetWrapper: AssetWrapper;
+    constructor(assetWrapper: AssetWrapper) {
+        this._assetWrapper = assetWrapper;
+    }
+    public async getBalanceAsync(assetData: string, userAddress: string): Promise<BigNumber> {
+        const balance = await this._assetWrapper.getBalanceAsync(userAddress, assetData);
+        return balance;
+    }
+    public async getProxyAllowanceAsync(assetData: string, userAddress: string): Promise<BigNumber> {
+        const proxyAllowance = await this._assetWrapper.getProxyAllowanceAsync(userAddress, assetData);
+        return proxyAllowance;
+    }
+}
diff --git a/packages/contracts/src/utils/simple_order_filled_cancelled_fetcher.ts b/packages/contracts/src/utils/simple_order_filled_cancelled_fetcher.ts
new file mode 100644
index 000000000..24afe36b7
--- /dev/null
+++ b/packages/contracts/src/utils/simple_order_filled_cancelled_fetcher.ts
@@ -0,0 +1,24 @@
+import { AbstractOrderFilledCancelledFetcher } from '@0xproject/order-utils';
+import { BigNumber } from '@0xproject/utils';
+
+import { ExchangeWrapper } from './exchange_wrapper';
+
+export class SimpleOrderFilledCancelledFetcher implements AbstractOrderFilledCancelledFetcher {
+    private _exchangeWrapper: ExchangeWrapper;
+    private _zrxAssetData: string;
+    constructor(exchange: ExchangeWrapper, zrxAssetData: string) {
+        this._exchangeWrapper = exchange;
+        this._zrxAssetData = zrxAssetData;
+    }
+    public async getFilledTakerAmountAsync(orderHash: string): Promise<BigNumber> {
+        const filledTakerAmount = new BigNumber(await this._exchangeWrapper.getTakerAssetFilledAmountAsync(orderHash));
+        return filledTakerAmount;
+    }
+    public async isOrderCancelledAsync(orderHash: string): Promise<boolean> {
+        const isCancelled = await this._exchangeWrapper.isCancelledAsync(orderHash);
+        return isCancelled;
+    }
+    public getZRXAssetData(): string {
+        return this._zrxAssetData;
+    }
+}
diff --git a/packages/contracts/src/utils/types.ts b/packages/contracts/src/utils/types.ts
index 5dfac64fc..b792bb90a 100644
--- a/packages/contracts/src/utils/types.ts
+++ b/packages/contracts/src/utils/types.ts
@@ -150,3 +150,80 @@ export interface MatchOrder {
     leftSignature: string;
     rightSignature: string;
 }
+
+// Combinatorial testing types
+
+export enum FeeRecipientAddressScenario {
+    BurnAddress = 'BURN_ADDRESS',
+    EthUserAddress = 'ETH_USER_ADDRESS',
+}
+
+export enum OrderAssetAmountScenario {
+    Zero = 'ZERO',
+    Large = 'LARGE',
+    Small = 'SMALL',
+}
+
+export enum TakerScenario {
+    CorrectlySpecified = 'CORRECTLY_SPECIFIED',
+    IncorrectlySpecified = 'INCORRECTLY_SPECIFIED',
+    Unspecified = 'UNSPECIFIED',
+}
+
+export enum ExpirationTimeSecondsScenario {
+    InPast = 'IN_PAST',
+    InFuture = 'IN_FUTURE',
+}
+
+export enum AssetDataScenario {
+    ERC721 = 'ERC721',
+    ZRXFeeToken = 'ZRX_FEE_TOKEN',
+    ERC20FiveDecimals = 'ERC20_FIVE_DECIMALS',
+    ERC20NonZRXEighteenDecimals = 'ERC20_NON_ZRX_EIGHTEEN_DECIMALS',
+}
+
+export enum TakerAssetFillAmountScenario {
+    Zero = 'ZERO',
+    GreaterThanRemainingFillableTakerAssetAmount = 'GREATER_THAN_REMAINING_FILLABLE_TAKER_ASSET_AMOUNT',
+    LessThanRemainingFillableTakerAssetAmount = 'LESS_THAN_REMAINING_FILLABLE_TAKER_ASSET_AMOUNT',
+    ExactlyRemainingFillableTakerAssetAmount = 'EXACTLY_REMAINING_FILLABLE_TAKER_ASSET_AMOUNT',
+}
+
+export interface OrderScenario {
+    takerScenario: TakerScenario;
+    feeRecipientScenario: FeeRecipientAddressScenario;
+    makerAssetAmountScenario: OrderAssetAmountScenario;
+    takerAssetAmountScenario: OrderAssetAmountScenario;
+    makerFeeScenario: OrderAssetAmountScenario;
+    takerFeeScenario: OrderAssetAmountScenario;
+    expirationTimeSecondsScenario: ExpirationTimeSecondsScenario;
+    makerAssetDataScenario: AssetDataScenario;
+    takerAssetDataScenario: AssetDataScenario;
+}
+
+export enum BalanceAmountScenario {
+    Exact = 'EXACT',
+    TooLow = 'TOO_LOW',
+    Higher = 'HIGHER',
+}
+
+export enum AllowanceAmountScenario {
+    Exact = 'EXACT',
+    TooLow = 'TOO_LOW',
+    Higher = 'HIGHER',
+    Unlimited = 'UNLIMITED',
+}
+
+export interface TraderStateScenario {
+    traderAssetBalance: BalanceAmountScenario;
+    traderAssetAllowance: AllowanceAmountScenario;
+    zrxFeeBalance: BalanceAmountScenario;
+    zrxFeeAllowance: AllowanceAmountScenario;
+}
+
+export interface FillScenario {
+    orderScenario: OrderScenario;
+    takerAssetFillAmountScenario: TakerAssetFillAmountScenario;
+    makerStateScenario: TraderStateScenario;
+    takerStateScenario: TraderStateScenario;
+}
diff --git a/packages/contracts/test/asset_proxy/proxies.ts b/packages/contracts/test/asset_proxy/proxies.ts
index 595839519..39121d95c 100644
--- a/packages/contracts/test/asset_proxy/proxies.ts
+++ b/packages/contracts/test/asset_proxy/proxies.ts
@@ -5,6 +5,7 @@ import { BigNumber } from '@0xproject/utils';
 import * as chai from 'chai';
 import { LogWithDecodedArgs } from 'ethereum-types';
 import ethUtil = require('ethereumjs-util');
+import * as _ from 'lodash';
 
 import { DummyERC20TokenContract } from '../../src/generated_contract_wrappers/dummy_e_r_c20_token';
 import {
@@ -53,12 +54,17 @@ describe('Asset Transfer Proxies', () => {
     });
     before(async () => {
         const accounts = await web3Wrapper.getAvailableAddressesAsync();
-        const usedAddresses = ([owner, notAuthorized, exchangeAddress, makerAddress, takerAddress] = accounts);
+        const usedAddresses = ([owner, notAuthorized, exchangeAddress, makerAddress, takerAddress] = _.slice(
+            accounts,
+            0,
+            5,
+        ));
 
         erc20Wrapper = new ERC20Wrapper(provider, usedAddresses, owner);
         erc721Wrapper = new ERC721Wrapper(provider, usedAddresses, owner);
 
-        [zrxToken] = await erc20Wrapper.deployDummyTokensAsync();
+        const numDummyErc20ToDeploy = 1;
+        [zrxToken] = await erc20Wrapper.deployDummyTokensAsync(numDummyErc20ToDeploy, constants.DUMMY_TOKEN_DECIMALS);
         erc20Proxy = await erc20Wrapper.deployProxyAsync();
         await erc20Wrapper.setBalancesAndAllowancesAsync();
         await web3Wrapper.awaitTransactionSuccessAsync(
diff --git a/packages/contracts/test/exchange/core.ts b/packages/contracts/test/exchange/core.ts
index 36f6fa8d3..0c7381aac 100644
--- a/packages/contracts/test/exchange/core.ts
+++ b/packages/contracts/test/exchange/core.ts
@@ -6,16 +6,13 @@ import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import * as chai from 'chai';
 import { LogWithDecodedArgs } from 'ethereum-types';
 import ethUtil = require('ethereumjs-util');
+import * as _ from 'lodash';
 
 import { DummyERC20TokenContract } from '../../src/generated_contract_wrappers/dummy_e_r_c20_token';
 import { DummyERC721TokenContract } from '../../src/generated_contract_wrappers/dummy_e_r_c721_token';
 import { ERC20ProxyContract } from '../../src/generated_contract_wrappers/e_r_c20_proxy';
 import { ERC721ProxyContract } from '../../src/generated_contract_wrappers/e_r_c721_proxy';
-import {
-    CancelContractEventArgs,
-    ExchangeContract,
-    FillContractEventArgs,
-} from '../../src/generated_contract_wrappers/exchange';
+import { CancelContractEventArgs, ExchangeContract } from '../../src/generated_contract_wrappers/exchange';
 import { artifacts } from '../../src/utils/artifacts';
 import { expectRevertReasonOrAlwaysFailingTransactionAsync } from '../../src/utils/assertions';
 import { chaiSetup } from '../../src/utils/chai_setup';
@@ -66,12 +63,16 @@ describe('Exchange core', () => {
     });
     before(async () => {
         const accounts = await web3Wrapper.getAvailableAddressesAsync();
-        const usedAddresses = ([owner, makerAddress, takerAddress, feeRecipientAddress] = accounts);
+        const usedAddresses = ([owner, makerAddress, takerAddress, feeRecipientAddress] = _.slice(accounts, 0, 4));
 
         erc20Wrapper = new ERC20Wrapper(provider, usedAddresses, owner);
         erc721Wrapper = new ERC721Wrapper(provider, usedAddresses, owner);
 
-        [erc20TokenA, erc20TokenB, zrxToken] = await erc20Wrapper.deployDummyTokensAsync();
+        const numDummyErc20ToDeploy = 3;
+        [erc20TokenA, erc20TokenB, zrxToken] = await erc20Wrapper.deployDummyTokensAsync(
+            numDummyErc20ToDeploy,
+            constants.DUMMY_TOKEN_DECIMALS,
+        );
         erc20Proxy = await erc20Wrapper.deployProxyAsync();
         await erc20Wrapper.setBalancesAndAllowancesAsync();
 
@@ -130,296 +131,6 @@ describe('Exchange core', () => {
             erc20Balances = await erc20Wrapper.getBalancesAsync();
             signedOrder = orderFactory.newSignedOrder();
         });
-        it('should transfer the correct amounts when makerAssetAmount === takerAssetAmount', async () => {
-            signedOrder = orderFactory.newSignedOrder({
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
-            });
-
-            const takerAssetFilledAmountBefore = await exchangeWrapper.getTakerAssetFilledAmountAsync(
-                orderHashUtils.getOrderHashHex(signedOrder),
-            );
-            expect(takerAssetFilledAmountBefore).to.be.bignumber.equal(0);
-
-            const takerAssetFillAmount = signedOrder.takerAssetAmount.div(2);
-            await exchangeWrapper.fillOrderAsync(signedOrder, takerAddress, { takerAssetFillAmount });
-
-            const makerAmountBoughtAfter = await exchangeWrapper.getTakerAssetFilledAmountAsync(
-                orderHashUtils.getOrderHashHex(signedOrder),
-            );
-            expect(makerAmountBoughtAfter).to.be.bignumber.equal(takerAssetFillAmount);
-
-            const newBalances = await erc20Wrapper.getBalancesAsync();
-
-            const makerAssetFilledAmount = takerAssetFillAmount
-                .times(signedOrder.makerAssetAmount)
-                .dividedToIntegerBy(signedOrder.takerAssetAmount);
-            const makerFeePaid = signedOrder.makerFee
-                .times(makerAssetFilledAmount)
-                .dividedToIntegerBy(signedOrder.makerAssetAmount);
-            const takerFeePaid = signedOrder.takerFee
-                .times(makerAssetFilledAmount)
-                .dividedToIntegerBy(signedOrder.makerAssetAmount);
-            expect(newBalances[makerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[makerAddress][defaultMakerAssetAddress].minus(makerAssetFilledAmount),
-            );
-            expect(newBalances[makerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[makerAddress][defaultTakerAssetAddress].add(takerAssetFillAmount),
-            );
-            expect(newBalances[makerAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[makerAddress][zrxToken.address].minus(makerFeePaid),
-            );
-            expect(newBalances[takerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[takerAddress][defaultTakerAssetAddress].minus(takerAssetFillAmount),
-            );
-            expect(newBalances[takerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[takerAddress][defaultMakerAssetAddress].add(makerAssetFilledAmount),
-            );
-            expect(newBalances[takerAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[takerAddress][zrxToken.address].minus(takerFeePaid),
-            );
-            expect(newBalances[feeRecipientAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[feeRecipientAddress][zrxToken.address].add(makerFeePaid.add(takerFeePaid)),
-            );
-        });
-
-        it('should transfer the correct amounts when makerAssetAmount > takerAssetAmount', async () => {
-            signedOrder = orderFactory.newSignedOrder({
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(200), 18),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
-            });
-
-            const takerAssetFilledAmountBefore = await exchangeWrapper.getTakerAssetFilledAmountAsync(
-                orderHashUtils.getOrderHashHex(signedOrder),
-            );
-            expect(takerAssetFilledAmountBefore).to.be.bignumber.equal(0);
-
-            const takerAssetFillAmount = signedOrder.takerAssetAmount.div(2);
-            await exchangeWrapper.fillOrderAsync(signedOrder, takerAddress, { takerAssetFillAmount });
-
-            const makerAmountBoughtAfter = await exchangeWrapper.getTakerAssetFilledAmountAsync(
-                orderHashUtils.getOrderHashHex(signedOrder),
-            );
-            expect(makerAmountBoughtAfter).to.be.bignumber.equal(takerAssetFillAmount);
-
-            const newBalances = await erc20Wrapper.getBalancesAsync();
-
-            const makerAssetFilledAmount = takerAssetFillAmount
-                .times(signedOrder.makerAssetAmount)
-                .dividedToIntegerBy(signedOrder.takerAssetAmount);
-            const makerFeePaid = signedOrder.makerFee
-                .times(makerAssetFilledAmount)
-                .dividedToIntegerBy(signedOrder.makerAssetAmount);
-            const takerFeePaid = signedOrder.takerFee
-                .times(makerAssetFilledAmount)
-                .dividedToIntegerBy(signedOrder.makerAssetAmount);
-            expect(newBalances[makerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[makerAddress][defaultMakerAssetAddress].minus(makerAssetFilledAmount),
-            );
-            expect(newBalances[makerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[makerAddress][defaultTakerAssetAddress].add(takerAssetFillAmount),
-            );
-            expect(newBalances[makerAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[makerAddress][zrxToken.address].minus(makerFeePaid),
-            );
-            expect(newBalances[takerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[takerAddress][defaultTakerAssetAddress].minus(takerAssetFillAmount),
-            );
-            expect(newBalances[takerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[takerAddress][defaultMakerAssetAddress].add(makerAssetFilledAmount),
-            );
-            expect(newBalances[takerAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[takerAddress][zrxToken.address].minus(takerFeePaid),
-            );
-            expect(newBalances[feeRecipientAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[feeRecipientAddress][zrxToken.address].add(makerFeePaid.add(takerFeePaid)),
-            );
-        });
-
-        it('should transfer the correct amounts when makerAssetAmount < takerAssetAmount', async () => {
-            signedOrder = orderFactory.newSignedOrder({
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(200), 18),
-            });
-
-            const takerAssetFilledAmountBefore = await exchangeWrapper.getTakerAssetFilledAmountAsync(
-                orderHashUtils.getOrderHashHex(signedOrder),
-            );
-            expect(takerAssetFilledAmountBefore).to.be.bignumber.equal(0);
-
-            const takerAssetFillAmount = signedOrder.takerAssetAmount.div(2);
-            await exchangeWrapper.fillOrderAsync(signedOrder, takerAddress, { takerAssetFillAmount });
-
-            const makerAmountBoughtAfter = await exchangeWrapper.getTakerAssetFilledAmountAsync(
-                orderHashUtils.getOrderHashHex(signedOrder),
-            );
-            expect(makerAmountBoughtAfter).to.be.bignumber.equal(takerAssetFillAmount);
-
-            const newBalances = await erc20Wrapper.getBalancesAsync();
-
-            const makerAssetFilledAmount = takerAssetFillAmount
-                .times(signedOrder.makerAssetAmount)
-                .dividedToIntegerBy(signedOrder.takerAssetAmount);
-            const makerFeePaid = signedOrder.makerFee
-                .times(makerAssetFilledAmount)
-                .dividedToIntegerBy(signedOrder.makerAssetAmount);
-            const takerFeePaid = signedOrder.takerFee
-                .times(makerAssetFilledAmount)
-                .dividedToIntegerBy(signedOrder.makerAssetAmount);
-            expect(newBalances[makerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[makerAddress][defaultMakerAssetAddress].minus(makerAssetFilledAmount),
-            );
-            expect(newBalances[makerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[makerAddress][defaultTakerAssetAddress].add(takerAssetFillAmount),
-            );
-            expect(newBalances[makerAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[makerAddress][zrxToken.address].minus(makerFeePaid),
-            );
-            expect(newBalances[takerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[takerAddress][defaultTakerAssetAddress].minus(takerAssetFillAmount),
-            );
-            expect(newBalances[takerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[takerAddress][defaultMakerAssetAddress].add(makerAssetFilledAmount),
-            );
-            expect(newBalances[takerAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[takerAddress][zrxToken.address].minus(takerFeePaid),
-            );
-            expect(newBalances[feeRecipientAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[feeRecipientAddress][zrxToken.address].add(makerFeePaid.add(takerFeePaid)),
-            );
-        });
-
-        it('should transfer the correct amounts when taker is specified and order is claimed by taker', async () => {
-            signedOrder = orderFactory.newSignedOrder({
-                takerAddress,
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(200), 18),
-            });
-
-            const takerAssetFilledAmountBefore = await exchangeWrapper.getTakerAssetFilledAmountAsync(
-                orderHashUtils.getOrderHashHex(signedOrder),
-            );
-            expect(takerAssetFilledAmountBefore).to.be.bignumber.equal(0);
-
-            const takerAssetFillAmount = signedOrder.takerAssetAmount.div(2);
-            await exchangeWrapper.fillOrderAsync(signedOrder, takerAddress, { takerAssetFillAmount });
-
-            const makerAmountBoughtAfter = await exchangeWrapper.getTakerAssetFilledAmountAsync(
-                orderHashUtils.getOrderHashHex(signedOrder),
-            );
-            const expectedMakerAmountBoughtAfter = takerAssetFillAmount.add(takerAssetFilledAmountBefore);
-            expect(makerAmountBoughtAfter).to.be.bignumber.equal(expectedMakerAmountBoughtAfter);
-
-            const newBalances = await erc20Wrapper.getBalancesAsync();
-
-            const makerAssetFilledAmount = takerAssetFillAmount
-                .times(signedOrder.makerAssetAmount)
-                .dividedToIntegerBy(signedOrder.takerAssetAmount);
-            const makerFeePaid = signedOrder.makerFee
-                .times(makerAssetFilledAmount)
-                .dividedToIntegerBy(signedOrder.makerAssetAmount);
-            const takerFeePaid = signedOrder.takerFee
-                .times(makerAssetFilledAmount)
-                .dividedToIntegerBy(signedOrder.makerAssetAmount);
-            expect(newBalances[makerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[makerAddress][defaultMakerAssetAddress].minus(makerAssetFilledAmount),
-            );
-            expect(newBalances[makerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[makerAddress][defaultTakerAssetAddress].add(takerAssetFillAmount),
-            );
-            expect(newBalances[makerAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[makerAddress][zrxToken.address].minus(makerFeePaid),
-            );
-            expect(newBalances[takerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[takerAddress][defaultTakerAssetAddress].minus(takerAssetFillAmount),
-            );
-            expect(newBalances[takerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[takerAddress][defaultMakerAssetAddress].add(makerAssetFilledAmount),
-            );
-            expect(newBalances[takerAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[takerAddress][zrxToken.address].minus(takerFeePaid),
-            );
-            expect(newBalances[feeRecipientAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[feeRecipientAddress][zrxToken.address].add(makerFeePaid.add(takerFeePaid)),
-            );
-        });
-
-        it('should fill remaining value if takerAssetFillAmount > remaining takerAssetAmount', async () => {
-            const takerAssetFillAmount = signedOrder.takerAssetAmount.div(2);
-            await exchangeWrapper.fillOrderAsync(signedOrder, takerAddress, { takerAssetFillAmount });
-
-            const res = await exchangeWrapper.fillOrderAsync(signedOrder, takerAddress, {
-                takerAssetFillAmount: signedOrder.takerAssetAmount,
-            });
-            const log = res.logs[0] as LogWithDecodedArgs<FillContractEventArgs>;
-            expect(log.args.takerAssetFilledAmount).to.be.bignumber.equal(
-                signedOrder.takerAssetAmount.minus(takerAssetFillAmount),
-            );
-            const newBalances = await erc20Wrapper.getBalancesAsync();
-
-            expect(newBalances[makerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[makerAddress][defaultMakerAssetAddress].minus(signedOrder.makerAssetAmount),
-            );
-            expect(newBalances[makerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[makerAddress][defaultTakerAssetAddress].add(signedOrder.takerAssetAmount),
-            );
-            expect(newBalances[makerAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[makerAddress][zrxToken.address].minus(signedOrder.makerFee),
-            );
-            expect(newBalances[takerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[takerAddress][defaultTakerAssetAddress].minus(signedOrder.takerAssetAmount),
-            );
-            expect(newBalances[takerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[takerAddress][defaultMakerAssetAddress].add(signedOrder.makerAssetAmount),
-            );
-            expect(newBalances[takerAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[takerAddress][zrxToken.address].minus(signedOrder.takerFee),
-            );
-            expect(newBalances[feeRecipientAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[feeRecipientAddress][zrxToken.address].add(
-                    signedOrder.makerFee.add(signedOrder.takerFee),
-                ),
-            );
-        });
-
-        it('should log 1 event with the correct arguments when order has a feeRecipient', async () => {
-            const divisor = 2;
-            const res = await exchangeWrapper.fillOrderAsync(signedOrder, takerAddress, {
-                takerAssetFillAmount: signedOrder.takerAssetAmount.div(divisor),
-            });
-            expect(res.logs).to.have.length(1);
-
-            const log = res.logs[0] as LogWithDecodedArgs<FillContractEventArgs>;
-            const logArgs = log.args;
-            const expectedFilledMakerAssetAmount = signedOrder.makerAssetAmount.div(divisor);
-            const expectedFilledTakerAssetAmount = signedOrder.takerAssetAmount.div(divisor);
-            const expectedFeeMPaid = signedOrder.makerFee.div(divisor);
-            const expectedFeeTPaid = signedOrder.takerFee.div(divisor);
-
-            expect(signedOrder.makerAddress).to.be.equal(logArgs.makerAddress);
-            expect(takerAddress).to.be.equal(logArgs.takerAddress);
-            expect(takerAddress).to.be.equal(logArgs.senderAddress);
-            expect(signedOrder.feeRecipientAddress).to.be.equal(logArgs.feeRecipientAddress);
-            expect(signedOrder.makerAssetData).to.be.equal(logArgs.makerAssetData);
-            expect(signedOrder.takerAssetData).to.be.equal(logArgs.takerAssetData);
-            expect(expectedFilledMakerAssetAmount).to.be.bignumber.equal(logArgs.makerAssetFilledAmount);
-            expect(expectedFilledTakerAssetAmount).to.be.bignumber.equal(logArgs.takerAssetFilledAmount);
-            expect(expectedFeeMPaid).to.be.bignumber.equal(logArgs.makerFeePaid);
-            expect(expectedFeeTPaid).to.be.bignumber.equal(logArgs.takerFeePaid);
-            expect(orderHashUtils.getOrderHashHex(signedOrder)).to.be.equal(logArgs.orderHash);
-        });
-
-        it('should throw when taker is specified and order is claimed by other', async () => {
-            signedOrder = orderFactory.newSignedOrder({
-                takerAddress: feeRecipientAddress,
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(200), 18),
-            });
-            return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                exchangeWrapper.fillOrderAsync(signedOrder, takerAddress),
-                RevertReason.InvalidTaker,
-            );
-        });
 
         it('should throw if signature is invalid', async () => {
             signedOrder = orderFactory.newSignedOrder({
@@ -439,96 +150,6 @@ describe('Exchange core', () => {
             );
         });
 
-        it('should throw if makerAssetAmount is 0', async () => {
-            signedOrder = orderFactory.newSignedOrder({
-                makerAssetAmount: new BigNumber(0),
-            });
-
-            return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                exchangeWrapper.fillOrderAsync(signedOrder, takerAddress),
-                RevertReason.OrderUnfillable,
-            );
-        });
-
-        it('should throw if takerAssetAmount is 0', async () => {
-            signedOrder = orderFactory.newSignedOrder({
-                takerAssetAmount: new BigNumber(0),
-            });
-
-            return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                exchangeWrapper.fillOrderAsync(signedOrder, takerAddress),
-                RevertReason.OrderUnfillable,
-            );
-        });
-
-        it('should throw if takerAssetFillAmount is 0', async () => {
-            signedOrder = orderFactory.newSignedOrder();
-
-            return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                exchangeWrapper.fillOrderAsync(signedOrder, takerAddress, {
-                    takerAssetFillAmount: new BigNumber(0),
-                }),
-                RevertReason.InvalidTakerAmount,
-            );
-        });
-
-        it('should throw if maker erc20Balances are too low to fill order', async () => {
-            signedOrder = orderFactory.newSignedOrder({
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100000), 18),
-            });
-
-            return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                exchangeWrapper.fillOrderAsync(signedOrder, takerAddress),
-                RevertReason.TransferFailed,
-            );
-        });
-
-        it('should throw if taker erc20Balances are too low to fill order', async () => {
-            signedOrder = orderFactory.newSignedOrder({
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100000), 18),
-            });
-            return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                exchangeWrapper.fillOrderAsync(signedOrder, takerAddress),
-                RevertReason.TransferFailed,
-            );
-        });
-
-        it('should throw if maker allowances are too low to fill order', async () => {
-            await web3Wrapper.awaitTransactionSuccessAsync(
-                await erc20TokenA.approve.sendTransactionAsync(erc20Proxy.address, new BigNumber(0), {
-                    from: makerAddress,
-                }),
-                constants.AWAIT_TRANSACTION_MINED_MS,
-            );
-            return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                exchangeWrapper.fillOrderAsync(signedOrder, takerAddress),
-                RevertReason.TransferFailed,
-            );
-        });
-
-        it('should throw if taker allowances are too low to fill order', async () => {
-            await web3Wrapper.awaitTransactionSuccessAsync(
-                await erc20TokenB.approve.sendTransactionAsync(erc20Proxy.address, new BigNumber(0), {
-                    from: takerAddress,
-                }),
-                constants.AWAIT_TRANSACTION_MINED_MS,
-            );
-            return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                exchangeWrapper.fillOrderAsync(signedOrder, takerAddress),
-                RevertReason.TransferFailed,
-            );
-        });
-
-        it('should throw if an order is expired', async () => {
-            signedOrder = orderFactory.newSignedOrder({
-                expirationTimeSeconds: new BigNumber(Math.floor((Date.now() - 10000) / 1000)),
-            });
-            return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                exchangeWrapper.fillOrderAsync(signedOrder, takerAddress),
-                RevertReason.OrderUnfillable,
-            );
-        });
-
         it('should throw if no value is filled', async () => {
             signedOrder = orderFactory.newSignedOrder();
             await exchangeWrapper.fillOrderAsync(signedOrder, takerAddress);
@@ -725,32 +346,6 @@ describe('Exchange core', () => {
     });
 
     describe('Testing Exchange of ERC721 Tokens', () => {
-        it('should successfully exchange a single token between the maker and taker (via fillOrder)', async () => {
-            // Construct Exchange parameters
-            const makerAssetId = erc721MakerAssetIds[0];
-            const takerAssetId = erc721TakerAssetIds[1];
-            signedOrder = orderFactory.newSignedOrder({
-                makerAssetAmount: new BigNumber(1),
-                takerAssetAmount: new BigNumber(1),
-                makerAssetData: assetProxyUtils.encodeERC721AssetData(erc721Token.address, makerAssetId),
-                takerAssetData: assetProxyUtils.encodeERC721AssetData(erc721Token.address, takerAssetId),
-            });
-            // Verify pre-conditions
-            const initialOwnerMakerAsset = await erc721Token.ownerOf.callAsync(makerAssetId);
-            expect(initialOwnerMakerAsset).to.be.bignumber.equal(makerAddress);
-            const initialOwnerTakerAsset = await erc721Token.ownerOf.callAsync(takerAssetId);
-            expect(initialOwnerTakerAsset).to.be.bignumber.equal(takerAddress);
-            // Call Exchange
-            const takerAssetFillAmount = signedOrder.takerAssetAmount;
-            // tslint:disable-next-line:no-unused-variable
-            const res = await exchangeWrapper.fillOrderAsync(signedOrder, takerAddress, { takerAssetFillAmount });
-            // Verify post-conditions
-            const newOwnerMakerAsset = await erc721Token.ownerOf.callAsync(makerAssetId);
-            expect(newOwnerMakerAsset).to.be.bignumber.equal(takerAddress);
-            const newOwnerTakerAsset = await erc721Token.ownerOf.callAsync(takerAssetId);
-            expect(newOwnerTakerAsset).to.be.bignumber.equal(makerAddress);
-        });
-
         it('should throw when maker does not own the token with id makerAssetId', async () => {
             // Construct Exchange parameters
             const makerAssetId = erc721TakerAssetIds[0];
@@ -885,86 +480,6 @@ describe('Exchange core', () => {
                 RevertReason.LengthGreaterThan131Required,
             );
         });
-
-        it('should successfully fill order when makerAsset is ERC721 and takerAsset is ERC20', async () => {
-            // Construct Exchange parameters
-            const makerAssetId = erc721MakerAssetIds[0];
-            signedOrder = orderFactory.newSignedOrder({
-                makerAssetAmount: new BigNumber(1),
-                takerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
-                makerAssetData: assetProxyUtils.encodeERC721AssetData(erc721Token.address, makerAssetId),
-                takerAssetData: assetProxyUtils.encodeERC20AssetData(defaultTakerAssetAddress),
-            });
-            // Verify pre-conditions
-            const initialOwnerMakerAsset = await erc721Token.ownerOf.callAsync(makerAssetId);
-            expect(initialOwnerMakerAsset).to.be.bignumber.equal(makerAddress);
-            // Call Exchange
-            erc20Balances = await erc20Wrapper.getBalancesAsync();
-            const takerAssetFillAmount = signedOrder.takerAssetAmount;
-            await exchangeWrapper.fillOrderAsync(signedOrder, takerAddress, { takerAssetFillAmount });
-            // Verify ERC721 token was transferred from Maker to Taker
-            const newOwnerMakerAsset = await erc721Token.ownerOf.callAsync(makerAssetId);
-            expect(newOwnerMakerAsset).to.be.bignumber.equal(takerAddress);
-            // Verify ERC20 tokens were transferred from Taker to Maker & fees were paid correctly
-            const newBalances = await erc20Wrapper.getBalancesAsync();
-            expect(newBalances[makerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[makerAddress][defaultTakerAssetAddress].add(takerAssetFillAmount),
-            );
-            expect(newBalances[takerAddress][defaultTakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[takerAddress][defaultTakerAssetAddress].minus(takerAssetFillAmount),
-            );
-            expect(newBalances[makerAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[makerAddress][zrxToken.address].minus(signedOrder.makerFee),
-            );
-            expect(newBalances[takerAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[takerAddress][zrxToken.address].minus(signedOrder.takerFee),
-            );
-            expect(newBalances[feeRecipientAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[feeRecipientAddress][zrxToken.address].add(
-                    signedOrder.makerFee.add(signedOrder.takerFee),
-                ),
-            );
-        });
-
-        it('should successfully fill order when makerAsset is ERC20 and takerAsset is ERC721', async () => {
-            // Construct Exchange parameters
-            const takerAssetId = erc721TakerAssetIds[0];
-            signedOrder = orderFactory.newSignedOrder({
-                takerAssetAmount: new BigNumber(1),
-                makerAssetAmount: Web3Wrapper.toBaseUnitAmount(new BigNumber(100), 18),
-                takerAssetData: assetProxyUtils.encodeERC721AssetData(erc721Token.address, takerAssetId),
-                makerAssetData: assetProxyUtils.encodeERC20AssetData(defaultMakerAssetAddress),
-            });
-            // Verify pre-conditions
-            const initialOwnerTakerAsset = await erc721Token.ownerOf.callAsync(takerAssetId);
-            expect(initialOwnerTakerAsset).to.be.bignumber.equal(takerAddress);
-            // Call Exchange
-            erc20Balances = await erc20Wrapper.getBalancesAsync();
-            const takerAssetFillAmount = signedOrder.takerAssetAmount;
-            await exchangeWrapper.fillOrderAsync(signedOrder, takerAddress, { takerAssetFillAmount });
-            // Verify ERC721 token was transferred from Taker to Maker
-            const newOwnerTakerAsset = await erc721Token.ownerOf.callAsync(takerAssetId);
-            expect(newOwnerTakerAsset).to.be.bignumber.equal(makerAddress);
-            // Verify ERC20 tokens were transferred from Maker to Taker & fees were paid correctly
-            const newBalances = await erc20Wrapper.getBalancesAsync();
-            expect(newBalances[takerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[takerAddress][defaultMakerAssetAddress].add(signedOrder.makerAssetAmount),
-            );
-            expect(newBalances[makerAddress][defaultMakerAssetAddress]).to.be.bignumber.equal(
-                erc20Balances[makerAddress][defaultMakerAssetAddress].minus(signedOrder.makerAssetAmount),
-            );
-            expect(newBalances[makerAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[makerAddress][zrxToken.address].minus(signedOrder.makerFee),
-            );
-            expect(newBalances[takerAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[takerAddress][zrxToken.address].minus(signedOrder.takerFee),
-            );
-            expect(newBalances[feeRecipientAddress][zrxToken.address]).to.be.bignumber.equal(
-                erc20Balances[feeRecipientAddress][zrxToken.address].add(
-                    signedOrder.makerFee.add(signedOrder.takerFee),
-                ),
-            );
-        });
     });
 });
 // tslint:disable:max-file-line-count
diff --git a/packages/contracts/test/exchange/dispatcher.ts b/packages/contracts/test/exchange/dispatcher.ts
index 8adbee6a3..e35cca845 100644
--- a/packages/contracts/test/exchange/dispatcher.ts
+++ b/packages/contracts/test/exchange/dispatcher.ts
@@ -3,6 +3,7 @@ import { assetProxyUtils } from '@0xproject/order-utils';
 import { AssetProxyId, RevertReason } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import * as chai from 'chai';
+import * as _ from 'lodash';
 
 import { DummyERC20TokenContract } from '../../src/generated_contract_wrappers/dummy_e_r_c20_token';
 import { ERC20ProxyContract } from '../../src/generated_contract_wrappers/e_r_c20_proxy';
@@ -43,12 +44,13 @@ describe('AssetProxyDispatcher', () => {
     before(async () => {
         // Setup accounts & addresses
         const accounts = await web3Wrapper.getAvailableAddressesAsync();
-        const usedAddresses = ([owner, notOwner, makerAddress, takerAddress] = accounts);
+        const usedAddresses = ([owner, notOwner, makerAddress, takerAddress] = _.slice(accounts, 0, 4));
 
         erc20Wrapper = new ERC20Wrapper(provider, usedAddresses, owner);
         erc721Wrapper = new ERC721Wrapper(provider, usedAddresses, owner);
 
-        [zrxToken] = await erc20Wrapper.deployDummyTokensAsync();
+        const numDummyErc20ToDeploy = 1;
+        [zrxToken] = await erc20Wrapper.deployDummyTokensAsync(numDummyErc20ToDeploy, constants.DUMMY_TOKEN_DECIMALS);
         erc20Proxy = await erc20Wrapper.deployProxyAsync();
         await erc20Wrapper.setBalancesAndAllowancesAsync();
 
diff --git a/packages/contracts/test/exchange/fill_order.ts b/packages/contracts/test/exchange/fill_order.ts
new file mode 100644
index 000000000..d65ab2f9a
--- /dev/null
+++ b/packages/contracts/test/exchange/fill_order.ts
@@ -0,0 +1,306 @@
+import { BlockchainLifecycle } from '@0xproject/dev-utils';
+import * as _ from 'lodash';
+
+import { chaiSetup } from '../../src/utils/chai_setup';
+import { CoreCombinatorialUtils, coreCombinatorialUtilsFactoryAsync } from '../../src/utils/core_combinatorial_utils';
+import { provider, txDefaults, web3Wrapper } from '../../src/utils/web3_wrapper';
+
+import {
+    AllowanceAmountScenario,
+    AssetDataScenario,
+    BalanceAmountScenario,
+    ExpirationTimeSecondsScenario,
+    FeeRecipientAddressScenario,
+    FillScenario,
+    OrderAssetAmountScenario,
+    TakerAssetFillAmountScenario,
+    TakerScenario,
+} from '../../src/utils/types';
+
+chaiSetup.configure();
+const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
+
+const defaultFillScenario = {
+    orderScenario: {
+        takerScenario: TakerScenario.Unspecified,
+        feeRecipientScenario: FeeRecipientAddressScenario.EthUserAddress,
+        makerAssetAmountScenario: OrderAssetAmountScenario.Large,
+        takerAssetAmountScenario: OrderAssetAmountScenario.Large,
+        makerFeeScenario: OrderAssetAmountScenario.Large,
+        takerFeeScenario: OrderAssetAmountScenario.Large,
+        expirationTimeSecondsScenario: ExpirationTimeSecondsScenario.InFuture,
+        makerAssetDataScenario: AssetDataScenario.ERC20NonZRXEighteenDecimals,
+        takerAssetDataScenario: AssetDataScenario.ERC20NonZRXEighteenDecimals,
+    },
+    takerAssetFillAmountScenario: TakerAssetFillAmountScenario.LessThanRemainingFillableTakerAssetAmount,
+    makerStateScenario: {
+        traderAssetBalance: BalanceAmountScenario.Higher,
+        traderAssetAllowance: AllowanceAmountScenario.Higher,
+        zrxFeeBalance: BalanceAmountScenario.Higher,
+        zrxFeeAllowance: AllowanceAmountScenario.Higher,
+    },
+    takerStateScenario: {
+        traderAssetBalance: BalanceAmountScenario.Higher,
+        traderAssetAllowance: AllowanceAmountScenario.Higher,
+        zrxFeeBalance: BalanceAmountScenario.Higher,
+        zrxFeeAllowance: AllowanceAmountScenario.Higher,
+    },
+};
+
+describe('FillOrder Tests', () => {
+    let coreCombinatorialUtils: CoreCombinatorialUtils;
+
+    before(async () => {
+        await blockchainLifecycle.startAsync();
+        coreCombinatorialUtils = await coreCombinatorialUtilsFactoryAsync(web3Wrapper, txDefaults);
+    });
+    after(async () => {
+        await blockchainLifecycle.revertAsync();
+    });
+    beforeEach(async () => {
+        await blockchainLifecycle.startAsync();
+    });
+    afterEach(async () => {
+        await blockchainLifecycle.revertAsync();
+    });
+    describe('fillOrder', () => {
+        const test = (fillScenarios: FillScenario[]) => {
+            _.forEach(fillScenarios, fillScenario => {
+                const orderScenario = fillScenario.orderScenario;
+                const description = `Combinatorial OrderFill: ${orderScenario.feeRecipientScenario} ${
+                    orderScenario.makerAssetAmountScenario
+                } ${orderScenario.takerAssetAmountScenario} ${orderScenario.makerFeeScenario} ${
+                    orderScenario.takerFeeScenario
+                } ${orderScenario.expirationTimeSecondsScenario} ${orderScenario.makerAssetDataScenario} ${
+                    orderScenario.takerAssetDataScenario
+                }`;
+                it(description, async () => {
+                    await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario);
+                });
+            });
+        };
+
+        const allFillScenarios = CoreCombinatorialUtils.generateFillOrderCombinations();
+        describe('Combinatorially generated fills orders', () => test(allFillScenarios));
+
+        it('should transfer the correct amounts when makerAssetAmount === takerAssetAmount', async () => {
+            const fillScenario = {
+                ...defaultFillScenario,
+            };
+            await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario);
+        });
+        it('should transfer the correct amounts when makerAssetAmount > takerAssetAmount', async () => {
+            const fillScenario = {
+                ...defaultFillScenario,
+                orderScenario: {
+                    ...defaultFillScenario.orderScenario,
+                    takerAssetAmountScenario: OrderAssetAmountScenario.Small,
+                },
+            };
+            await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario);
+        });
+        it('should transfer the correct amounts when makerAssetAmount < takerAssetAmount', async () => {
+            const fillScenario = {
+                ...defaultFillScenario,
+                orderScenario: {
+                    ...defaultFillScenario.orderScenario,
+                    makerAssetAmountScenario: OrderAssetAmountScenario.Small,
+                },
+            };
+            await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario);
+        });
+        it('should transfer the correct amounts when taker is specified and order is claimed by taker', async () => {
+            const fillScenario = {
+                ...defaultFillScenario,
+                orderScenario: {
+                    ...defaultFillScenario.orderScenario,
+                    takerScenario: TakerScenario.CorrectlySpecified,
+                },
+            };
+            await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario);
+        });
+        it('should fill remaining value if takerAssetFillAmount > remaining takerAssetAmount', async () => {
+            const fillScenario = {
+                ...defaultFillScenario,
+                takerAssetFillAmountScenario: TakerAssetFillAmountScenario.GreaterThanRemainingFillableTakerAssetAmount,
+            };
+            await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario);
+        });
+        it('should throw when taker is specified and order is claimed by other', async () => {
+            const fillScenario = {
+                ...defaultFillScenario,
+                orderScenario: {
+                    ...defaultFillScenario.orderScenario,
+                    takerScenario: TakerScenario.IncorrectlySpecified,
+                },
+            };
+            await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario);
+        });
+
+        it('should throw if makerAssetAmount is 0', async () => {
+            const fillScenario = {
+                ...defaultFillScenario,
+                orderScenario: {
+                    ...defaultFillScenario.orderScenario,
+                    makerAssetAmountScenario: OrderAssetAmountScenario.Zero,
+                },
+                takerAssetFillAmountScenario: TakerAssetFillAmountScenario.GreaterThanRemainingFillableTakerAssetAmount,
+            };
+            await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario);
+        });
+
+        it('should throw if takerAssetAmount is 0', async () => {
+            const fillScenario = {
+                ...defaultFillScenario,
+                orderScenario: {
+                    ...defaultFillScenario.orderScenario,
+                    takerAssetAmountScenario: OrderAssetAmountScenario.Zero,
+                },
+                takerAssetFillAmountScenario: TakerAssetFillAmountScenario.GreaterThanRemainingFillableTakerAssetAmount,
+            };
+            await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario);
+        });
+
+        it('should throw if takerAssetFillAmount is 0', async () => {
+            const fillScenario = {
+                ...defaultFillScenario,
+                takerAssetFillAmountScenario: TakerAssetFillAmountScenario.Zero,
+            };
+            await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario);
+        });
+
+        it('should throw if an order is expired', async () => {
+            const fillScenario = {
+                ...defaultFillScenario,
+                orderScenario: {
+                    ...defaultFillScenario.orderScenario,
+                    expirationTimeSecondsScenario: ExpirationTimeSecondsScenario.InPast,
+                },
+            };
+            await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario);
+        });
+
+        it('should throw if maker erc20Balances are too low to fill order', async () => {
+            const fillScenario = {
+                ...defaultFillScenario,
+                makerStateScenario: {
+                    ...defaultFillScenario.makerStateScenario,
+                    traderAssetBalance: BalanceAmountScenario.TooLow,
+                },
+            };
+            await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario);
+        });
+
+        it('should throw if taker erc20Balances are too low to fill order', async () => {
+            const fillScenario = {
+                ...defaultFillScenario,
+                takerStateScenario: {
+                    ...defaultFillScenario.makerStateScenario,
+                    traderAssetBalance: BalanceAmountScenario.TooLow,
+                },
+            };
+            await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario);
+        });
+
+        it('should throw if maker allowances are too low to fill order', async () => {
+            const fillScenario = {
+                ...defaultFillScenario,
+                makerStateScenario: {
+                    ...defaultFillScenario.makerStateScenario,
+                    traderAssetAllowance: AllowanceAmountScenario.TooLow,
+                },
+            };
+            await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario);
+        });
+
+        it('should throw if taker allowances are too low to fill order', async () => {
+            const fillScenario = {
+                ...defaultFillScenario,
+                takerStateScenario: {
+                    ...defaultFillScenario.makerStateScenario,
+                    traderAssetAllowance: AllowanceAmountScenario.TooLow,
+                },
+            };
+            await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario);
+        });
+    });
+
+    describe('Testing Exchange of ERC721 Tokens', () => {
+        it('should successfully exchange a single token between the maker and taker (via fillOrder)', async () => {
+            const fillScenario = {
+                ...defaultFillScenario,
+                orderScenario: {
+                    ...defaultFillScenario.orderScenario,
+                    makerAssetDataScenario: AssetDataScenario.ERC721,
+                    takerAssetDataScenario: AssetDataScenario.ERC721,
+                },
+                takerAssetFillAmountScenario: TakerAssetFillAmountScenario.ExactlyRemainingFillableTakerAssetAmount,
+            };
+            await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario);
+        });
+
+        it('should successfully fill order when makerAsset is ERC721 and takerAsset is ERC20', async () => {
+            const fillScenario = {
+                ...defaultFillScenario,
+                orderScenario: {
+                    ...defaultFillScenario.orderScenario,
+                    makerAssetDataScenario: AssetDataScenario.ERC721,
+                    takerAssetDataScenario: AssetDataScenario.ERC20NonZRXEighteenDecimals,
+                },
+                takerAssetFillAmountScenario: TakerAssetFillAmountScenario.ExactlyRemainingFillableTakerAssetAmount,
+            };
+            await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario, true);
+        });
+
+        it('should successfully fill order when makerAsset is ERC20 and takerAsset is ERC721', async () => {
+            const fillScenario = {
+                ...defaultFillScenario,
+                orderScenario: {
+                    ...defaultFillScenario.orderScenario,
+                    makerAssetDataScenario: AssetDataScenario.ERC20NonZRXEighteenDecimals,
+                    takerAssetDataScenario: AssetDataScenario.ERC721,
+                },
+                takerAssetFillAmountScenario: TakerAssetFillAmountScenario.ExactlyRemainingFillableTakerAssetAmount,
+            };
+            await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario);
+        });
+
+        it('should successfully fill order when makerAsset is ERC721 and approveAll is set for it', async () => {
+            const fillScenario = {
+                ...defaultFillScenario,
+                orderScenario: {
+                    ...defaultFillScenario.orderScenario,
+                    makerAssetDataScenario: AssetDataScenario.ERC721,
+                    takerAssetDataScenario: AssetDataScenario.ERC20NonZRXEighteenDecimals,
+                },
+                takerAssetFillAmountScenario: TakerAssetFillAmountScenario.ExactlyRemainingFillableTakerAssetAmount,
+                makerStateScenario: {
+                    ...defaultFillScenario.makerStateScenario,
+                    traderAssetAllowance: AllowanceAmountScenario.Unlimited,
+                },
+            };
+            await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario);
+        });
+
+        it('should successfully fill order when makerAsset and takerAsset are ERC721 and approveAll is set for them', async () => {
+            const fillScenario = {
+                ...defaultFillScenario,
+                orderScenario: {
+                    ...defaultFillScenario.orderScenario,
+                    makerAssetDataScenario: AssetDataScenario.ERC721,
+                    takerAssetDataScenario: AssetDataScenario.ERC721,
+                },
+                takerAssetFillAmountScenario: TakerAssetFillAmountScenario.ExactlyRemainingFillableTakerAssetAmount,
+                makerStateScenario: {
+                    ...defaultFillScenario.makerStateScenario,
+                    traderAssetAllowance: AllowanceAmountScenario.Unlimited,
+                },
+                takerStateScenario: {
+                    ...defaultFillScenario.takerStateScenario,
+                    traderAssetAllowance: AllowanceAmountScenario.Unlimited,
+                },
+            };
+            await coreCombinatorialUtils.testFillOrderScenarioAsync(provider, fillScenario);
+        });
+    });
+});
diff --git a/packages/contracts/test/exchange/match_orders.ts b/packages/contracts/test/exchange/match_orders.ts
index bcf691471..e23ab9851 100644
--- a/packages/contracts/test/exchange/match_orders.ts
+++ b/packages/contracts/test/exchange/match_orders.ts
@@ -76,12 +76,16 @@ describe('matchOrders', () => {
             takerAddress,
             feeRecipientAddressLeft,
             feeRecipientAddressRight,
-        ] = accounts);
+        ] = _.slice(accounts, 0, 6));
         // Create wrappers
         erc20Wrapper = new ERC20Wrapper(provider, usedAddresses, owner);
         erc721Wrapper = new ERC721Wrapper(provider, usedAddresses, owner);
         // Deploy ERC20 token & ERC20 proxy
-        [erc20TokenA, erc20TokenB, zrxToken] = await erc20Wrapper.deployDummyTokensAsync();
+        const numDummyErc20ToDeploy = 3;
+        [erc20TokenA, erc20TokenB, zrxToken] = await erc20Wrapper.deployDummyTokensAsync(
+            numDummyErc20ToDeploy,
+            constants.DUMMY_TOKEN_DECIMALS,
+        );
         erc20Proxy = await erc20Wrapper.deployProxyAsync();
         await erc20Wrapper.setBalancesAndAllowancesAsync();
         // Deploy ERC721 token and proxy
diff --git a/packages/contracts/test/exchange/transactions.ts b/packages/contracts/test/exchange/transactions.ts
index b0c08e46e..c4de58bb9 100644
--- a/packages/contracts/test/exchange/transactions.ts
+++ b/packages/contracts/test/exchange/transactions.ts
@@ -3,6 +3,7 @@ import { assetProxyUtils, generatePseudoRandomSalt } from '@0xproject/order-util
 import { AssetProxyId, OrderWithoutExchangeAddress, RevertReason, SignedOrder } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import * as chai from 'chai';
+import * as _ from 'lodash';
 
 import { DummyERC20TokenContract } from '../../src/generated_contract_wrappers/dummy_e_r_c20_token';
 import { ERC20ProxyContract } from '../../src/generated_contract_wrappers/e_r_c20_proxy';
@@ -67,11 +68,19 @@ describe('Exchange transactions', () => {
     });
     before(async () => {
         const accounts = await web3Wrapper.getAvailableAddressesAsync();
-        const usedAddresses = ([owner, senderAddress, makerAddress, takerAddress, feeRecipientAddress] = accounts);
+        const usedAddresses = ([owner, senderAddress, makerAddress, takerAddress, feeRecipientAddress] = _.slice(
+            accounts,
+            0,
+            5,
+        ));
 
         erc20Wrapper = new ERC20Wrapper(provider, usedAddresses, owner);
 
-        [erc20TokenA, erc20TokenB, zrxToken] = await erc20Wrapper.deployDummyTokensAsync();
+        const numDummyErc20ToDeploy = 3;
+        [erc20TokenA, erc20TokenB, zrxToken] = await erc20Wrapper.deployDummyTokensAsync(
+            numDummyErc20ToDeploy,
+            constants.DUMMY_TOKEN_DECIMALS,
+        );
         erc20Proxy = await erc20Wrapper.deployProxyAsync();
         await erc20Wrapper.setBalancesAndAllowancesAsync();
 
diff --git a/packages/contracts/test/exchange/wrapper.ts b/packages/contracts/test/exchange/wrapper.ts
index 9ee68f94d..1af8bde9d 100644
--- a/packages/contracts/test/exchange/wrapper.ts
+++ b/packages/contracts/test/exchange/wrapper.ts
@@ -60,12 +60,16 @@ describe('Exchange wrappers', () => {
     });
     before(async () => {
         const accounts = await web3Wrapper.getAvailableAddressesAsync();
-        const usedAddresses = ([owner, makerAddress, takerAddress, feeRecipientAddress] = accounts);
+        const usedAddresses = ([owner, makerAddress, takerAddress, feeRecipientAddress] = _.slice(accounts, 0, 4));
 
         erc20Wrapper = new ERC20Wrapper(provider, usedAddresses, owner);
         erc721Wrapper = new ERC721Wrapper(provider, usedAddresses, owner);
 
-        [erc20TokenA, erc20TokenB, zrxToken] = await erc20Wrapper.deployDummyTokensAsync();
+        const numDummyErc20ToDeploy = 3;
+        [erc20TokenA, erc20TokenB, zrxToken] = await erc20Wrapper.deployDummyTokensAsync(
+            numDummyErc20ToDeploy,
+            constants.DUMMY_TOKEN_DECIMALS,
+        );
         erc20Proxy = await erc20Wrapper.deployProxyAsync();
         await erc20Wrapper.setBalancesAndAllowancesAsync();
 
@@ -370,7 +374,7 @@ describe('Exchange wrappers', () => {
                 // HACK(albrow): We need to hardcode the gas estimate here because
                 // the Geth gas estimator doesn't work with the way we use
                 // delegatecall and swallow errors.
-                gas: 270000,
+                gas: 280000,
             });
             // Verify post-conditions
             const newOwnerMakerAsset = await erc721Token.ownerOf.callAsync(makerAssetId);
diff --git a/packages/order-utils/src/abstract/abstract_order_filled_cancelled_fetcher.ts b/packages/order-utils/src/abstract/abstract_order_filled_cancelled_fetcher.ts
index ec398a11e..865ea4e43 100644
--- a/packages/order-utils/src/abstract/abstract_order_filled_cancelled_fetcher.ts
+++ b/packages/order-utils/src/abstract/abstract_order_filled_cancelled_fetcher.ts
@@ -3,5 +3,5 @@ import { BigNumber } from '@0xproject/utils';
 export abstract class AbstractOrderFilledCancelledFetcher {
     public abstract async getFilledTakerAmountAsync(orderHash: string): Promise<BigNumber>;
     public abstract async isOrderCancelledAsync(orderHash: string): Promise<boolean>;
-    public abstract getZRXTokenAddress(): string;
+    public abstract getZRXAssetData(): string;
 }
diff --git a/packages/order-utils/src/exchange_transfer_simulator.ts b/packages/order-utils/src/exchange_transfer_simulator.ts
index 32d53d6a2..72ed85406 100644
--- a/packages/order-utils/src/exchange_transfer_simulator.ts
+++ b/packages/order-utils/src/exchange_transfer_simulator.ts
@@ -90,6 +90,9 @@ export class ExchangeTransferSimulator {
         amountInBaseUnits: BigNumber,
     ): Promise<void> {
         const proxyAllowance = await this._store.getProxyAllowanceAsync(assetData, userAddress);
+        // HACK: This code assumes that all tokens with an UNLIMITED_ALLOWANCE_IN_BASE_UNITS set,
+        // are UnlimitedAllowanceTokens. This is however not true, it just so happens that all
+        // DummyERC20Tokens we use in tests are.
         if (!proxyAllowance.eq(constants.UNLIMITED_ALLOWANCE_IN_BASE_UNITS)) {
             this._store.setProxyAllowance(assetData, userAddress, proxyAllowance.minus(amountInBaseUnits));
         }
diff --git a/packages/order-utils/src/index.ts b/packages/order-utils/src/index.ts
index 514488e02..b4a7a6b67 100644
--- a/packages/order-utils/src/index.ts
+++ b/packages/order-utils/src/index.ts
@@ -16,6 +16,7 @@ export { generatePseudoRandomSalt } from './salt';
 export { OrderError, MessagePrefixType, MessagePrefixOpts, EIP712Parameter, EIP712Schema, EIP712Types } from './types';
 export { AbstractBalanceAndProxyAllowanceFetcher } from './abstract/abstract_balance_and_proxy_allowance_fetcher';
 export { AbstractOrderFilledCancelledFetcher } from './abstract/abstract_order_filled_cancelled_fetcher';
+export { BalanceAndProxyAllowanceLazyStore } from './store/balance_and_proxy_allowance_lazy_store';
 export { RemainingFillableCalculator } from './remaining_fillable_calculator';
 export { OrderStateUtils } from './order_state_utils';
 export { assetProxyUtils } from './asset_proxy_utils';
diff --git a/packages/order-utils/src/order_state_utils.ts b/packages/order-utils/src/order_state_utils.ts
index 40f235da7..dd45a1298 100644
--- a/packages/order-utils/src/order_state_utils.ts
+++ b/packages/order-utils/src/order_state_utils.ts
@@ -10,40 +10,81 @@ import { BigNumber } from '@0xproject/utils';
 
 import { AbstractBalanceAndProxyAllowanceFetcher } from './abstract/abstract_balance_and_proxy_allowance_fetcher';
 import { AbstractOrderFilledCancelledFetcher } from './abstract/abstract_order_filled_cancelled_fetcher';
-import { assetProxyUtils } from './asset_proxy_utils';
 import { orderHashUtils } from './order_hash';
 import { RemainingFillableCalculator } from './remaining_fillable_calculator';
+import { utils } from './utils';
+
+interface SidedOrderRelevantState {
+    isMakerSide: boolean;
+    traderBalance: BigNumber;
+    traderProxyAllowance: BigNumber;
+    traderFeeBalance: BigNumber;
+    traderFeeProxyAllowance: BigNumber;
+    filledTakerAssetAmount: BigNumber;
+    remainingFillableAssetAmount: BigNumber;
+}
 
 const ACCEPTABLE_RELATIVE_ROUNDING_ERROR = 0.0001;
 
 export class OrderStateUtils {
     private _balanceAndProxyAllowanceFetcher: AbstractBalanceAndProxyAllowanceFetcher;
     private _orderFilledCancelledFetcher: AbstractOrderFilledCancelledFetcher;
-    private static _validateIfOrderIsValid(signedOrder: SignedOrder, orderRelevantState: OrderRelevantState): void {
-        const availableTakerAssetAmount = signedOrder.takerAssetAmount.minus(orderRelevantState.filledTakerAssetAmount);
+    private static _validateIfOrderIsValid(
+        signedOrder: SignedOrder,
+        sidedOrderRelevantState: SidedOrderRelevantState,
+    ): void {
+        const isMakerSide = sidedOrderRelevantState.isMakerSide;
+        const availableTakerAssetAmount = signedOrder.takerAssetAmount.minus(
+            sidedOrderRelevantState.filledTakerAssetAmount,
+        );
         if (availableTakerAssetAmount.eq(0)) {
             throw new Error(ExchangeContractErrs.OrderRemainingFillAmountZero);
         }
 
-        if (orderRelevantState.makerBalance.eq(0)) {
-            throw new Error(ExchangeContractErrs.InsufficientMakerBalance);
+        if (sidedOrderRelevantState.traderBalance.eq(0)) {
+            throw new Error(
+                isMakerSide
+                    ? ExchangeContractErrs.InsufficientMakerBalance
+                    : ExchangeContractErrs.InsufficientTakerBalance,
+            );
         }
-        if (orderRelevantState.makerProxyAllowance.eq(0)) {
-            throw new Error(ExchangeContractErrs.InsufficientMakerAllowance);
+        if (sidedOrderRelevantState.traderProxyAllowance.eq(0)) {
+            throw new Error(
+                isMakerSide
+                    ? ExchangeContractErrs.InsufficientMakerAllowance
+                    : ExchangeContractErrs.InsufficientTakerAllowance,
+            );
         }
         if (!signedOrder.makerFee.eq(0)) {
-            if (orderRelevantState.makerFeeBalance.eq(0)) {
-                throw new Error(ExchangeContractErrs.InsufficientMakerFeeBalance);
+            if (sidedOrderRelevantState.traderFeeBalance.eq(0)) {
+                throw new Error(
+                    isMakerSide
+                        ? ExchangeContractErrs.InsufficientMakerFeeBalance
+                        : ExchangeContractErrs.InsufficientTakerFeeBalance,
+                );
             }
-            if (orderRelevantState.makerFeeProxyAllowance.eq(0)) {
-                throw new Error(ExchangeContractErrs.InsufficientMakerFeeAllowance);
+            if (sidedOrderRelevantState.traderFeeProxyAllowance.eq(0)) {
+                throw new Error(
+                    isMakerSide
+                        ? ExchangeContractErrs.InsufficientMakerFeeAllowance
+                        : ExchangeContractErrs.InsufficientTakerFeeAllowance,
+                );
             }
         }
-        const minFillableTakerAssetAmountWithinNoRoundingErrorRange = signedOrder.takerAssetAmount
-            .dividedBy(ACCEPTABLE_RELATIVE_ROUNDING_ERROR)
-            .dividedBy(signedOrder.makerAssetAmount);
+
+        let minFillableTakerAssetAmountWithinNoRoundingErrorRange;
+        if (isMakerSide) {
+            minFillableTakerAssetAmountWithinNoRoundingErrorRange = signedOrder.takerAssetAmount
+                .dividedBy(ACCEPTABLE_RELATIVE_ROUNDING_ERROR)
+                .dividedBy(signedOrder.makerAssetAmount);
+        } else {
+            minFillableTakerAssetAmountWithinNoRoundingErrorRange = signedOrder.makerAssetAmount
+                .dividedBy(ACCEPTABLE_RELATIVE_ROUNDING_ERROR)
+                .dividedBy(signedOrder.takerAssetAmount);
+        }
+
         if (
-            orderRelevantState.remainingFillableTakerAssetAmount.lessThan(
+            sidedOrderRelevantState.remainingFillableAssetAmount.lessThan(
                 minFillableTakerAssetAmountWithinNoRoundingErrorRange,
             )
         ) {
@@ -57,11 +98,20 @@ export class OrderStateUtils {
         this._balanceAndProxyAllowanceFetcher = balanceAndProxyAllowanceFetcher;
         this._orderFilledCancelledFetcher = orderFilledCancelledFetcher;
     }
-    public async getOrderStateAsync(signedOrder: SignedOrder): Promise<OrderState> {
-        const orderRelevantState = await this.getOrderRelevantStateAsync(signedOrder);
+    public async getOpenOrderStateAsync(signedOrder: SignedOrder): Promise<OrderState> {
+        const orderRelevantState = await this.getOpenOrderRelevantStateAsync(signedOrder);
         const orderHash = orderHashUtils.getOrderHashHex(signedOrder);
+        const sidedOrderRelevantState = {
+            isMakerSide: true,
+            traderBalance: orderRelevantState.makerBalance,
+            traderProxyAllowance: orderRelevantState.makerProxyAllowance,
+            traderFeeBalance: orderRelevantState.makerFeeBalance,
+            traderFeeProxyAllowance: orderRelevantState.makerFeeProxyAllowance,
+            filledTakerAssetAmount: orderRelevantState.filledTakerAssetAmount,
+            remainingFillableAssetAmount: orderRelevantState.remainingFillableMakerAssetAmount,
+        };
         try {
-            OrderStateUtils._validateIfOrderIsValid(signedOrder, orderRelevantState);
+            OrderStateUtils._validateIfOrderIsValid(signedOrder, sidedOrderRelevantState);
             const orderState: OrderStateValid = {
                 isValid: true,
                 orderHash,
@@ -77,63 +127,158 @@ export class OrderStateUtils {
             return orderState;
         }
     }
-    public async getOrderRelevantStateAsync(signedOrder: SignedOrder): Promise<OrderRelevantState> {
-        const zrxTokenAddress = this._orderFilledCancelledFetcher.getZRXTokenAddress();
-        const makerProxyData = assetProxyUtils.decodeERC20AssetData(signedOrder.makerAssetData);
-        const makerAssetAddress = makerProxyData.tokenAddress;
-        const orderHash = orderHashUtils.getOrderHashHex(signedOrder);
-        const makerBalance = await this._balanceAndProxyAllowanceFetcher.getBalanceAsync(
-            makerAssetAddress,
-            signedOrder.makerAddress,
+    public async getOpenOrderRelevantStateAsync(signedOrder: SignedOrder): Promise<OrderRelevantState> {
+        const isMaker = true;
+        const sidedOrderRelevantState = await this._getSidedOrderRelevantStateAsync(
+            isMaker,
+            signedOrder,
+            signedOrder.takerAddress,
         );
-        const makerProxyAllowance = await this._balanceAndProxyAllowanceFetcher.getProxyAllowanceAsync(
-            makerAssetAddress,
-            signedOrder.makerAddress,
+        const remainingFillableTakerAssetAmount = sidedOrderRelevantState.remainingFillableAssetAmount
+            .times(signedOrder.takerAssetAmount)
+            .dividedToIntegerBy(signedOrder.makerAssetAmount);
+
+        const orderRelevantState = {
+            makerBalance: sidedOrderRelevantState.traderBalance,
+            makerProxyAllowance: sidedOrderRelevantState.traderProxyAllowance,
+            makerFeeBalance: sidedOrderRelevantState.traderFeeBalance,
+            makerFeeProxyAllowance: sidedOrderRelevantState.traderFeeProxyAllowance,
+            filledTakerAssetAmount: sidedOrderRelevantState.filledTakerAssetAmount,
+            remainingFillableMakerAssetAmount: sidedOrderRelevantState.remainingFillableAssetAmount,
+            remainingFillableTakerAssetAmount,
+        };
+        return orderRelevantState;
+    }
+    public async getMaxFillableTakerAssetAmountAsync(
+        signedOrder: SignedOrder,
+        takerAddress: string,
+    ): Promise<BigNumber> {
+        // Get max fillable amount for an order, considering the makers ability to fill
+        let isMaker = true;
+        const orderRelevantMakerState = await this._getSidedOrderRelevantStateAsync(
+            isMaker,
+            signedOrder,
+            signedOrder.takerAddress,
         );
-        const makerFeeBalance = await this._balanceAndProxyAllowanceFetcher.getBalanceAsync(
-            zrxTokenAddress,
-            signedOrder.makerAddress,
+        const remainingFillableTakerAssetAmountGivenMakersStatus = signedOrder.makerAssetAmount.eq(0)
+            ? new BigNumber(0)
+            : utils.getPartialAmount(
+                  orderRelevantMakerState.remainingFillableAssetAmount,
+                  signedOrder.makerAssetAmount,
+                  signedOrder.takerAssetAmount,
+              );
+
+        // Get max fillable amount for an order, considering the takers ability to fill
+        isMaker = false;
+        const orderRelevantTakerState = await this._getSidedOrderRelevantStateAsync(isMaker, signedOrder, takerAddress);
+        const remainingFillableTakerAssetAmountGivenTakersStatus = orderRelevantTakerState.remainingFillableAssetAmount;
+
+        // The min of these two in the actualy max fillable by either party
+        const fillableTakerAssetAmount = BigNumber.min([
+            remainingFillableTakerAssetAmountGivenMakersStatus,
+            remainingFillableTakerAssetAmountGivenTakersStatus,
+        ]);
+
+        return fillableTakerAssetAmount;
+    }
+    public async getMaxFillableTakerAssetAmountForFailingOrderAsync(
+        signedOrder: SignedOrder,
+        takerAddress: string,
+    ): Promise<BigNumber> {
+        // Get min of taker balance & allowance
+        const takerAssetBalanceOfTaker = await this._balanceAndProxyAllowanceFetcher.getBalanceAsync(
+            signedOrder.takerAssetData,
+            takerAddress,
         );
-        const makerFeeProxyAllowance = await this._balanceAndProxyAllowanceFetcher.getProxyAllowanceAsync(
-            zrxTokenAddress,
-            signedOrder.makerAddress,
+        const takerAssetAllowanceOfTaker = await this._balanceAndProxyAllowanceFetcher.getProxyAllowanceAsync(
+            signedOrder.takerAssetData,
+            takerAddress,
         );
+        const minTakerAssetAmount = BigNumber.min([takerAssetBalanceOfTaker, takerAssetAllowanceOfTaker]);
+
+        // get remainingFillAmount
+        const orderHash = orderHashUtils.getOrderHashHex(signedOrder);
+        const filledTakerAssetAmount = await this._orderFilledCancelledFetcher.getFilledTakerAmountAsync(orderHash);
+        const remainingFillTakerAssetAmount = signedOrder.takerAssetAmount.minus(filledTakerAssetAmount);
+
+        if (minTakerAssetAmount.gte(remainingFillTakerAssetAmount)) {
+            return remainingFillTakerAssetAmount;
+        } else {
+            return minTakerAssetAmount;
+        }
+    }
+    private async _getSidedOrderRelevantStateAsync(
+        isMakerSide: boolean,
+        signedOrder: SignedOrder,
+        takerAddress: string,
+    ): Promise<SidedOrderRelevantState> {
+        let traderAddress;
+        let assetData;
+        let assetAmount;
+        let feeAmount;
+        if (isMakerSide) {
+            traderAddress = signedOrder.makerAddress;
+            assetData = signedOrder.makerAssetData;
+            assetAmount = signedOrder.makerAssetAmount;
+            feeAmount = signedOrder.makerFee;
+        } else {
+            traderAddress = takerAddress;
+            assetData = signedOrder.takerAssetData;
+            assetAmount = signedOrder.takerAssetAmount;
+            feeAmount = signedOrder.takerFee;
+        }
+        const zrxAssetData = this._orderFilledCancelledFetcher.getZRXAssetData();
+        const isAssetZRX = assetData === zrxAssetData;
+
+        const traderBalance = await this._balanceAndProxyAllowanceFetcher.getBalanceAsync(assetData, traderAddress);
+        const traderProxyAllowance = await this._balanceAndProxyAllowanceFetcher.getProxyAllowanceAsync(
+            assetData,
+            traderAddress,
+        );
+        const traderFeeBalance = await this._balanceAndProxyAllowanceFetcher.getBalanceAsync(
+            zrxAssetData,
+            traderAddress,
+        );
+        const traderFeeProxyAllowance = await this._balanceAndProxyAllowanceFetcher.getProxyAllowanceAsync(
+            zrxAssetData,
+            traderAddress,
+        );
+
+        const transferrableTraderAssetAmount = BigNumber.min([traderProxyAllowance, traderBalance]);
+        const transferrableFeeAssetAmount = BigNumber.min([traderFeeProxyAllowance, traderFeeBalance]);
+
+        const orderHash = orderHashUtils.getOrderHashHex(signedOrder);
         const filledTakerAssetAmount = await this._orderFilledCancelledFetcher.getFilledTakerAmountAsync(orderHash);
-        const isOrderCancelled = await this._orderFilledCancelledFetcher.isOrderCancelledAsync(orderHash);
         const totalMakerAssetAmount = signedOrder.makerAssetAmount;
         const totalTakerAssetAmount = signedOrder.takerAssetAmount;
+        const isOrderCancelled = await this._orderFilledCancelledFetcher.isOrderCancelledAsync(orderHash);
         const remainingTakerAssetAmount = isOrderCancelled
             ? new BigNumber(0)
             : totalTakerAssetAmount.minus(filledTakerAssetAmount);
-        const remainingMakerAssetAmount = remainingTakerAssetAmount
-            .times(totalMakerAssetAmount)
-            .dividedToIntegerBy(totalTakerAssetAmount);
-        const transferrableMakerAssetAmount = BigNumber.min([makerProxyAllowance, makerBalance]);
-        const transferrableFeeAssetAmount = BigNumber.min([makerFeeProxyAllowance, makerFeeBalance]);
-
-        const zrxAssetData = assetProxyUtils.encodeERC20AssetData(zrxTokenAddress);
-        const isMakerAssetZRX = signedOrder.makerAssetData === zrxAssetData;
+        const remainingMakerAssetAmount = remainingTakerAssetAmount.eq(0)
+            ? new BigNumber(0)
+            : remainingTakerAssetAmount.times(totalMakerAssetAmount).dividedToIntegerBy(totalTakerAssetAmount);
+        const remainingAssetAmount = isMakerSide ? remainingMakerAssetAmount : remainingTakerAssetAmount;
+
         const remainingFillableCalculator = new RemainingFillableCalculator(
-            signedOrder.makerFee,
-            signedOrder.makerAssetAmount,
-            isMakerAssetZRX,
-            transferrableMakerAssetAmount,
+            feeAmount,
+            assetAmount,
+            isAssetZRX,
+            transferrableTraderAssetAmount,
             transferrableFeeAssetAmount,
-            remainingMakerAssetAmount,
+            remainingAssetAmount,
         );
-        const remainingFillableMakerAssetAmount = remainingFillableCalculator.computeRemainingFillable();
-        const remainingFillableTakerAssetAmount = remainingFillableMakerAssetAmount
-            .times(signedOrder.takerAssetAmount)
-            .dividedToIntegerBy(signedOrder.makerAssetAmount);
-        const orderRelevantState = {
-            makerBalance,
-            makerProxyAllowance,
-            makerFeeBalance,
-            makerFeeProxyAllowance,
+        const remainingFillableAssetAmount = remainingFillableCalculator.computeRemainingFillable();
+
+        const sidedOrderRelevantState = {
+            isMakerSide,
+            traderBalance,
+            traderProxyAllowance,
+            traderFeeBalance,
+            traderFeeProxyAllowance,
             filledTakerAssetAmount,
-            remainingFillableMakerAssetAmount,
-            remainingFillableTakerAssetAmount,
+            remainingFillableAssetAmount,
         };
-        return orderRelevantState;
+        return sidedOrderRelevantState;
     }
 }
diff --git a/packages/order-utils/src/order_validation_utils.ts b/packages/order-utils/src/order_validation_utils.ts
index 3a6704f26..54428f77d 100644
--- a/packages/order-utils/src/order_validation_utils.ts
+++ b/packages/order-utils/src/order_validation_utils.ts
@@ -1,24 +1,19 @@
-import { ExchangeContractErrs, Order, SignedOrder } from '@0xproject/types';
+import { RevertReason, SignedOrder } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import { Provider } from 'ethereum-types';
 import * as _ from 'lodash';
 
 import { OrderError, TradeSide, TransferType } from './types';
 
+import { AbstractOrderFilledCancelledFetcher } from './abstract/abstract_order_filled_cancelled_fetcher';
 import { constants } from './constants';
 import { ExchangeTransferSimulator } from './exchange_transfer_simulator';
-import { ExchangeContract } from './generated_contract_wrappers/exchange';
 import { orderHashUtils } from './order_hash';
 import { isValidSignatureAsync } from './signature_utils';
 import { utils } from './utils';
 
 export class OrderValidationUtils {
-    private _exchangeContract: ExchangeContract;
-    // TODO: Write some tests for the function
-    // const numerator = new BigNumber(20);
-    // const denominator = new BigNumber(999);
-    // const target = new BigNumber(50);
-    // rounding error = ((20*50/999) - floor(20*50/999)) / (20*50/999) = 0.1%
+    private _orderFilledCancelledFetcher: AbstractOrderFilledCancelledFetcher;
     public static isRoundingError(numerator: BigNumber, denominator: BigNumber, target: BigNumber): boolean {
         // Solidity's mulmod() in JS
         // Source: https://solidity.readthedocs.io/en/latest/units-and-global-variables.html#mathematical-and-cryptographic-functions
@@ -36,136 +31,120 @@ export class OrderValidationUtils {
         const isError = errPercentageTimes1000000.gt(1000);
         return isError;
     }
-    public static validateCancelOrderThrowIfInvalid(
-        order: Order,
-        cancelTakerTokenAmount: BigNumber,
-        filledTakerTokenAmount: BigNumber,
-    ): void {
-        if (cancelTakerTokenAmount.eq(0)) {
-            throw new Error(ExchangeContractErrs.OrderCancelAmountZero);
-        }
-        if (order.takerAssetAmount.eq(filledTakerTokenAmount)) {
-            throw new Error(ExchangeContractErrs.OrderAlreadyCancelledOrFilled);
-        }
-        const currentUnixTimestampSec = utils.getCurrentUnixTimestampSec();
-        if (order.expirationTimeSeconds.lessThan(currentUnixTimestampSec)) {
-            throw new Error(ExchangeContractErrs.OrderCancelExpired);
-        }
-    }
     public static async validateFillOrderBalancesAllowancesThrowIfInvalidAsync(
         exchangeTradeEmulator: ExchangeTransferSimulator,
         signedOrder: SignedOrder,
-        fillTakerTokenAmount: BigNumber,
+        fillTakerAssetAmount: BigNumber,
         senderAddress: string,
-        zrxTokenAddress: string,
+        zrxAssetData: string,
     ): Promise<void> {
-        const fillMakerTokenAmount = OrderValidationUtils._getPartialAmount(
-            fillTakerTokenAmount,
-            signedOrder.takerAssetAmount,
-            signedOrder.makerAssetAmount,
-        );
-        await exchangeTradeEmulator.transferFromAsync(
-            signedOrder.makerAssetData,
-            signedOrder.makerAddress,
-            senderAddress,
-            fillMakerTokenAmount,
-            TradeSide.Maker,
-            TransferType.Trade,
-        );
-        await exchangeTradeEmulator.transferFromAsync(
-            signedOrder.takerAssetData,
-            senderAddress,
-            signedOrder.makerAddress,
-            fillTakerTokenAmount,
-            TradeSide.Taker,
-            TransferType.Trade,
-        );
-        const makerFeeAmount = OrderValidationUtils._getPartialAmount(
-            fillTakerTokenAmount,
-            signedOrder.takerAssetAmount,
-            signedOrder.makerFee,
-        );
-        await exchangeTradeEmulator.transferFromAsync(
-            zrxTokenAddress,
-            signedOrder.makerAddress,
-            signedOrder.feeRecipientAddress,
-            makerFeeAmount,
-            TradeSide.Maker,
-            TransferType.Fee,
-        );
-        const takerFeeAmount = OrderValidationUtils._getPartialAmount(
-            fillTakerTokenAmount,
-            signedOrder.takerAssetAmount,
-            signedOrder.takerFee,
-        );
-        await exchangeTradeEmulator.transferFromAsync(
-            zrxTokenAddress,
-            senderAddress,
-            signedOrder.feeRecipientAddress,
-            takerFeeAmount,
-            TradeSide.Taker,
-            TransferType.Fee,
-        );
+        try {
+            const fillMakerTokenAmount = utils.getPartialAmount(
+                fillTakerAssetAmount,
+                signedOrder.takerAssetAmount,
+                signedOrder.makerAssetAmount,
+            );
+            await exchangeTradeEmulator.transferFromAsync(
+                signedOrder.makerAssetData,
+                signedOrder.makerAddress,
+                senderAddress,
+                fillMakerTokenAmount,
+                TradeSide.Maker,
+                TransferType.Trade,
+            );
+            await exchangeTradeEmulator.transferFromAsync(
+                signedOrder.takerAssetData,
+                senderAddress,
+                signedOrder.makerAddress,
+                fillTakerAssetAmount,
+                TradeSide.Taker,
+                TransferType.Trade,
+            );
+            const makerFeeAmount = utils.getPartialAmount(
+                fillTakerAssetAmount,
+                signedOrder.takerAssetAmount,
+                signedOrder.makerFee,
+            );
+            await exchangeTradeEmulator.transferFromAsync(
+                zrxAssetData,
+                signedOrder.makerAddress,
+                signedOrder.feeRecipientAddress,
+                makerFeeAmount,
+                TradeSide.Maker,
+                TransferType.Fee,
+            );
+            const takerFeeAmount = utils.getPartialAmount(
+                fillTakerAssetAmount,
+                signedOrder.takerAssetAmount,
+                signedOrder.takerFee,
+            );
+            await exchangeTradeEmulator.transferFromAsync(
+                zrxAssetData,
+                senderAddress,
+                signedOrder.feeRecipientAddress,
+                takerFeeAmount,
+                TradeSide.Taker,
+                TransferType.Fee,
+            );
+        } catch (err) {
+            throw new Error(RevertReason.TransferFailed);
+        }
     }
     private static _validateRemainingFillAmountNotZeroOrThrow(
         takerAssetAmount: BigNumber,
         filledTakerTokenAmount: BigNumber,
     ): void {
         if (takerAssetAmount.eq(filledTakerTokenAmount)) {
-            throw new Error(ExchangeContractErrs.OrderRemainingFillAmountZero);
+            throw new Error(RevertReason.OrderUnfillable);
         }
     }
     private static _validateOrderNotExpiredOrThrow(expirationTimeSeconds: BigNumber): void {
         const currentUnixTimestampSec = utils.getCurrentUnixTimestampSec();
         if (expirationTimeSeconds.lessThan(currentUnixTimestampSec)) {
-            throw new Error(ExchangeContractErrs.OrderFillExpired);
+            throw new Error(RevertReason.OrderUnfillable);
         }
     }
-    private static _getPartialAmount(numerator: BigNumber, denominator: BigNumber, target: BigNumber): BigNumber {
-        const fillMakerTokenAmount = numerator
-            .mul(target)
-            .div(denominator)
-            .round(0);
-        return fillMakerTokenAmount;
-    }
-    constructor(exchangeContract: ExchangeContract) {
-        this._exchangeContract = exchangeContract;
+    constructor(orderFilledCancelledFetcher: AbstractOrderFilledCancelledFetcher) {
+        this._orderFilledCancelledFetcher = orderFilledCancelledFetcher;
     }
     public async validateOrderFillableOrThrowAsync(
         exchangeTradeEmulator: ExchangeTransferSimulator,
         signedOrder: SignedOrder,
-        zrxTokenAddress: string,
+        zrxAssetData: string,
         expectedFillTakerTokenAmount?: BigNumber,
     ): Promise<void> {
         const orderHash = orderHashUtils.getOrderHashHex(signedOrder);
-        const filledTakerTokenAmount = await this._exchangeContract.filled.callAsync(orderHash);
+        const filledTakerTokenAmount = await this._orderFilledCancelledFetcher.getFilledTakerAmountAsync(orderHash);
         OrderValidationUtils._validateRemainingFillAmountNotZeroOrThrow(
             signedOrder.takerAssetAmount,
             filledTakerTokenAmount,
         );
         OrderValidationUtils._validateOrderNotExpiredOrThrow(signedOrder.expirationTimeSeconds);
-        let fillTakerTokenAmount = signedOrder.takerAssetAmount.minus(filledTakerTokenAmount);
+        let fillTakerAssetAmount = signedOrder.takerAssetAmount.minus(filledTakerTokenAmount);
         if (!_.isUndefined(expectedFillTakerTokenAmount)) {
-            fillTakerTokenAmount = expectedFillTakerTokenAmount;
+            fillTakerAssetAmount = expectedFillTakerTokenAmount;
         }
         await OrderValidationUtils.validateFillOrderBalancesAllowancesThrowIfInvalidAsync(
             exchangeTradeEmulator,
             signedOrder,
-            fillTakerTokenAmount,
+            fillTakerAssetAmount,
             signedOrder.takerAddress,
-            zrxTokenAddress,
+            zrxAssetData,
         );
     }
     public async validateFillOrderThrowIfInvalidAsync(
         exchangeTradeEmulator: ExchangeTransferSimulator,
         provider: Provider,
         signedOrder: SignedOrder,
-        fillTakerTokenAmount: BigNumber,
+        fillTakerAssetAmount: BigNumber,
         takerAddress: string,
-        zrxTokenAddress: string,
+        zrxAssetData: string,
     ): Promise<BigNumber> {
-        if (fillTakerTokenAmount.eq(0)) {
-            throw new Error(ExchangeContractErrs.OrderFillAmountZero);
+        if (fillTakerAssetAmount.eq(0)) {
+            throw new Error(RevertReason.InvalidTakerAmount);
+        }
+        if (signedOrder.makerAssetAmount.eq(0) || signedOrder.takerAssetAmount.eq(0)) {
+            throw new Error(RevertReason.OrderUnfillable);
         }
         const orderHash = orderHashUtils.getOrderHashHex(signedOrder);
         const isValid = await isValidSignatureAsync(
@@ -177,34 +156,34 @@ export class OrderValidationUtils {
         if (!isValid) {
             throw new Error(OrderError.InvalidSignature);
         }
-        const filledTakerTokenAmount = await this._exchangeContract.filled.callAsync(orderHash);
+        const filledTakerTokenAmount = await this._orderFilledCancelledFetcher.getFilledTakerAmountAsync(orderHash);
         OrderValidationUtils._validateRemainingFillAmountNotZeroOrThrow(
             signedOrder.takerAssetAmount,
             filledTakerTokenAmount,
         );
         if (signedOrder.takerAddress !== constants.NULL_ADDRESS && signedOrder.takerAddress !== takerAddress) {
-            throw new Error(ExchangeContractErrs.TransactionSenderIsNotFillOrderTaker);
+            throw new Error(RevertReason.InvalidTaker);
         }
         OrderValidationUtils._validateOrderNotExpiredOrThrow(signedOrder.expirationTimeSeconds);
         const remainingTakerTokenAmount = signedOrder.takerAssetAmount.minus(filledTakerTokenAmount);
-        const desiredFillTakerTokenAmount = remainingTakerTokenAmount.lessThan(fillTakerTokenAmount)
+        const desiredFillTakerTokenAmount = remainingTakerTokenAmount.lessThan(fillTakerAssetAmount)
             ? remainingTakerTokenAmount
-            : fillTakerTokenAmount;
+            : fillTakerAssetAmount;
         await OrderValidationUtils.validateFillOrderBalancesAllowancesThrowIfInvalidAsync(
             exchangeTradeEmulator,
             signedOrder,
             desiredFillTakerTokenAmount,
             takerAddress,
-            zrxTokenAddress,
+            zrxAssetData,
         );
 
         const wouldRoundingErrorOccur = OrderValidationUtils.isRoundingError(
-            filledTakerTokenAmount,
+            desiredFillTakerTokenAmount,
             signedOrder.takerAssetAmount,
             signedOrder.makerAssetAmount,
         );
         if (wouldRoundingErrorOccur) {
-            throw new Error(ExchangeContractErrs.OrderFillRoundingError);
+            throw new Error(RevertReason.RoundingError);
         }
         return filledTakerTokenAmount;
     }
@@ -212,20 +191,20 @@ export class OrderValidationUtils {
         exchangeTradeEmulator: ExchangeTransferSimulator,
         provider: Provider,
         signedOrder: SignedOrder,
-        fillTakerTokenAmount: BigNumber,
+        fillTakerAssetAmount: BigNumber,
         takerAddress: string,
-        zrxTokenAddress: string,
+        zrxAssetData: string,
     ): Promise<void> {
         const filledTakerTokenAmount = await this.validateFillOrderThrowIfInvalidAsync(
             exchangeTradeEmulator,
             provider,
             signedOrder,
-            fillTakerTokenAmount,
+            fillTakerAssetAmount,
             takerAddress,
-            zrxTokenAddress,
+            zrxAssetData,
         );
-        if (filledTakerTokenAmount !== fillTakerTokenAmount) {
-            throw new Error(ExchangeContractErrs.InsufficientRemainingFillAmount);
+        if (filledTakerTokenAmount !== fillTakerAssetAmount) {
+            throw new Error(RevertReason.OrderUnfillable);
         }
     }
 }
diff --git a/packages/order-utils/src/remaining_fillable_calculator.ts b/packages/order-utils/src/remaining_fillable_calculator.ts
index bc146e931..29e19e5ab 100644
--- a/packages/order-utils/src/remaining_fillable_calculator.ts
+++ b/packages/order-utils/src/remaining_fillable_calculator.ts
@@ -23,9 +23,9 @@ export class RemainingFillableCalculator {
         this._transferrableAssetAmount = transferrableAssetAmount;
         this._transferrableFeeAmount = transferrableFeeAmount;
         this._remainingOrderAssetAmount = remainingOrderAssetAmount;
-        this._remainingOrderFeeAmount = remainingOrderAssetAmount
-            .times(this._orderFee)
-            .dividedToIntegerBy(this._orderAssetAmount);
+        this._remainingOrderFeeAmount = orderAssetAmount.eq(0)
+            ? new BigNumber(0)
+            : remainingOrderAssetAmount.times(orderFee).dividedToIntegerBy(orderAssetAmount);
     }
     public computeRemainingFillable(): BigNumber {
         if (this._hasSufficientFundsForFeeAndTransferAmount()) {
diff --git a/packages/order-utils/src/store/balance_and_proxy_allowance_lazy_store.ts b/packages/order-utils/src/store/balance_and_proxy_allowance_lazy_store.ts
index 08d50b924..e7352119d 100644
--- a/packages/order-utils/src/store/balance_and_proxy_allowance_lazy_store.ts
+++ b/packages/order-utils/src/store/balance_and_proxy_allowance_lazy_store.ts
@@ -19,8 +19,8 @@ export class BalanceAndProxyAllowanceLazyStore implements AbstractBalanceAndProx
             [userAddress: string]: BigNumber;
         };
     };
-    constructor(token: AbstractBalanceAndProxyAllowanceFetcher) {
-        this._balanceAndProxyAllowanceFetcher = token;
+    constructor(balanceAndProxyAllowanceFetcher: AbstractBalanceAndProxyAllowanceFetcher) {
+        this._balanceAndProxyAllowanceFetcher = balanceAndProxyAllowanceFetcher;
         this._balance = {};
         this._proxyAllowance = {};
     }
diff --git a/packages/order-utils/src/utils.ts b/packages/order-utils/src/utils.ts
index 6149316f6..7aaaf0609 100644
--- a/packages/order-utils/src/utils.ts
+++ b/packages/order-utils/src/utils.ts
@@ -12,4 +12,11 @@ export const utils = {
         const milisecondsInSecond = 1000;
         return new BigNumber(Date.now() / milisecondsInSecond).round();
     },
+    getPartialAmount(numerator: BigNumber, denominator: BigNumber, target: BigNumber): BigNumber {
+        const fillMakerTokenAmount = numerator
+            .mul(target)
+            .div(denominator)
+            .round(0);
+        return fillMakerTokenAmount;
+    },
 };
diff --git a/packages/order-utils/test/exchange_transfer_simulator_test.ts b/packages/order-utils/test/exchange_transfer_simulator_test.ts
index 52385f611..bed04d879 100644
--- a/packages/order-utils/test/exchange_transfer_simulator_test.ts
+++ b/packages/order-utils/test/exchange_transfer_simulator_test.ts
@@ -4,6 +4,7 @@ import { BigNumber } from '@0xproject/utils';
 import * as chai from 'chai';
 
 import { artifacts } from '../src/artifacts';
+import { assetProxyUtils } from '../src/asset_proxy_utils';
 import { constants } from '../src/constants';
 import { ExchangeTransferSimulator } from '../src/exchange_transfer_simulator';
 import { DummyERC20TokenContract } from '../src/generated_contract_wrappers/dummy_e_r_c20_token';
@@ -27,7 +28,7 @@ describe('ExchangeTransferSimulator', async () => {
     let coinbase: string;
     let sender: string;
     let recipient: string;
-    let exampleTokenAddress: string;
+    let exampleAssetData: string;
     let exchangeTransferSimulator: ExchangeTransferSimulator;
     let txHash: string;
     let erc20ProxyAddress: string;
@@ -65,7 +66,7 @@ describe('ExchangeTransferSimulator', async () => {
             totalSupply,
         );
 
-        exampleTokenAddress = dummyERC20Token.address;
+        exampleAssetData = assetProxyUtils.encodeERC20AssetData(dummyERC20Token.address);
     });
     beforeEach(async () => {
         await blockchainLifecycle.startAsync();
@@ -91,7 +92,7 @@ describe('ExchangeTransferSimulator', async () => {
         it("throws if the user doesn't have enough allowance", async () => {
             return expect(
                 exchangeTransferSimulator.transferFromAsync(
-                    exampleTokenAddress,
+                    exampleAssetData,
                     sender,
                     recipient,
                     transferAmount,
@@ -107,7 +108,7 @@ describe('ExchangeTransferSimulator', async () => {
             await web3Wrapper.awaitTransactionSuccessAsync(txHash);
             return expect(
                 exchangeTransferSimulator.transferFromAsync(
-                    exampleTokenAddress,
+                    exampleAssetData,
                     sender,
                     recipient,
                     transferAmount,
@@ -128,7 +129,7 @@ describe('ExchangeTransferSimulator', async () => {
             await web3Wrapper.awaitTransactionSuccessAsync(txHash);
 
             await exchangeTransferSimulator.transferFromAsync(
-                exampleTokenAddress,
+                exampleAssetData,
                 sender,
                 recipient,
                 transferAmount,
@@ -136,9 +137,9 @@ describe('ExchangeTransferSimulator', async () => {
                 TransferType.Trade,
             );
             const store = (exchangeTransferSimulator as any)._store;
-            const senderBalance = await store.getBalanceAsync(exampleTokenAddress, sender);
-            const recipientBalance = await store.getBalanceAsync(exampleTokenAddress, recipient);
-            const senderProxyAllowance = await store.getProxyAllowanceAsync(exampleTokenAddress, sender);
+            const senderBalance = await store.getBalanceAsync(exampleAssetData, sender);
+            const recipientBalance = await store.getBalanceAsync(exampleAssetData, recipient);
+            const senderProxyAllowance = await store.getProxyAllowanceAsync(exampleAssetData, sender);
             expect(senderBalance).to.be.bignumber.equal(0);
             expect(recipientBalance).to.be.bignumber.equal(transferAmount);
             expect(senderProxyAllowance).to.be.bignumber.equal(0);
@@ -157,7 +158,7 @@ describe('ExchangeTransferSimulator', async () => {
             );
             await web3Wrapper.awaitTransactionSuccessAsync(txHash);
             await exchangeTransferSimulator.transferFromAsync(
-                exampleTokenAddress,
+                exampleAssetData,
                 sender,
                 recipient,
                 transferAmount,
@@ -165,9 +166,9 @@ describe('ExchangeTransferSimulator', async () => {
                 TransferType.Trade,
             );
             const store = (exchangeTransferSimulator as any)._store;
-            const senderBalance = await store.getBalanceAsync(exampleTokenAddress, sender);
-            const recipientBalance = await store.getBalanceAsync(exampleTokenAddress, recipient);
-            const senderProxyAllowance = await store.getProxyAllowanceAsync(exampleTokenAddress, sender);
+            const senderBalance = await store.getBalanceAsync(exampleAssetData, sender);
+            const recipientBalance = await store.getBalanceAsync(exampleAssetData, recipient);
+            const senderProxyAllowance = await store.getProxyAllowanceAsync(exampleAssetData, sender);
             expect(senderBalance).to.be.bignumber.equal(0);
             expect(recipientBalance).to.be.bignumber.equal(transferAmount);
             expect(senderProxyAllowance).to.be.bignumber.equal(constants.UNLIMITED_ALLOWANCE_IN_BASE_UNITS);
diff --git a/packages/order-watcher/test/global_hooks.ts b/packages/order-watcher/test/global_hooks.ts
index 9d6903af5..30b0cd697 100644
--- a/packages/order-watcher/test/global_hooks.ts
+++ b/packages/order-watcher/test/global_hooks.ts
@@ -6,7 +6,7 @@ import { provider } from './utils/web3_wrapper';
 before('migrate contracts', async function(): Promise<void> {
     // HACK: Since the migrations take longer then our global mocha timeout limit
     // we manually increase it for this before hook.
-    const mochaTestTimeoutMs = 20000;
+    const mochaTestTimeoutMs = 25000;
     this.timeout(mochaTestTimeoutMs);
     const txDefaults = {
         gas: devConstants.GAS_LIMIT,
diff --git a/packages/website/ts/blockchain.ts b/packages/website/ts/blockchain.ts
index 46a4d6629..d18c34c32 100644
--- a/packages/website/ts/blockchain.ts
+++ b/packages/website/ts/blockchain.ts
@@ -30,6 +30,7 @@ import {
 import { BigNumber, intervalUtils, logUtils, promisify } from '@0xproject/utils';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import * as _ from 'lodash';
+import * as moment from 'moment';
 import * as React from 'react';
 import contract = require('truffle-contract');
 import { BlockchainWatcher } from 'ts/blockchain_watcher';
@@ -43,6 +44,8 @@ import {
     BlockchainErrs,
     ContractInstance,
     Fill,
+    InjectedProviderObservable,
+    InjectedProviderUpdate,
     Order as PortalOrder,
     Providers,
     ProviderType,
@@ -79,9 +82,9 @@ export class Blockchain {
     private _dispatcher: Dispatcher;
     private _web3Wrapper?: Web3Wrapper;
     private _blockchainWatcher?: BlockchainWatcher;
+    private _injectedProviderObservable?: InjectedProviderObservable;
+    private _injectedProviderUpdateHandler: (update: InjectedProviderUpdate) => Promise<void>;
     private _userAddressIfExists: string;
-    private _cachedProvider: Provider;
-    private _cachedProviderNetworkId: number;
     private _ledgerSubprovider: LedgerSubprovider;
     private _defaultGasPrice: BigNumber;
     private static _getNameGivenProvider(provider: Provider): string {
@@ -92,16 +95,62 @@ export class Blockchain {
         }
         return providerNameIfExists;
     }
-    private static async _getProviderAsync(injectedWeb3: Web3, networkIdIfExists: number): Promise<Provider> {
+    private static _getInjectedWeb3(): any {
+        return (window as any).web3;
+    }
+    private static async _getInjectedWeb3ProviderNetworkIdIfExistsAsync(): Promise<number | undefined> {
+        // Hack: We need to know the networkId the injectedWeb3 is connected to (if it is defined) in
+        // order to properly instantiate the web3Wrapper. Since we must use the async call, we cannot
+        // retrieve it from within the web3Wrapper constructor. This is and should remain the only
+        // call to a web3 instance outside of web3Wrapper in the entire dapp.
+        // In addition, if the user has an injectedWeb3 instance that is disconnected from a backing
+        // Ethereum node, this call will throw. We need to handle this case gracefully
+        const injectedWeb3IfExists = Blockchain._getInjectedWeb3();
+        let networkIdIfExists: number;
+        if (!_.isUndefined(injectedWeb3IfExists)) {
+            try {
+                networkIdIfExists = _.parseInt(await promisify<string>(injectedWeb3IfExists.version.getNetwork)());
+            } catch (err) {
+                // Ignore error and proceed with networkId undefined
+            }
+        }
+        return networkIdIfExists;
+    }
+    private static async _getProviderAsync(
+        injectedWeb3: Web3,
+        networkIdIfExists: number,
+        shouldUserLedgerProvider: boolean = false,
+    ): Promise<[Provider, LedgerSubprovider | undefined]> {
         const doesInjectedWeb3Exist = !_.isUndefined(injectedWeb3);
+        const isNetworkIdAvailable = !_.isUndefined(networkIdIfExists);
         const publicNodeUrlsIfExistsForNetworkId = configs.PUBLIC_NODE_URLS_BY_NETWORK_ID[networkIdIfExists];
         const isPublicNodeAvailableForNetworkId = !_.isUndefined(publicNodeUrlsIfExistsForNetworkId);
 
-        let provider;
-        if (doesInjectedWeb3Exist && isPublicNodeAvailableForNetworkId) {
+        if (shouldUserLedgerProvider && isNetworkIdAvailable) {
+            const isU2FSupported = await utils.isU2FSupportedAsync();
+            if (!isU2FSupported) {
+                throw new Error('Cannot update providerType to LEDGER without U2F support');
+            }
+            const provider = new ProviderEngine();
+            const ledgerWalletConfigs = {
+                networkId: networkIdIfExists,
+                ledgerEthereumClientFactoryAsync: ledgerEthereumBrowserClientFactoryAsync,
+            };
+            const ledgerSubprovider = new LedgerSubprovider(ledgerWalletConfigs);
+            provider.addProvider(ledgerSubprovider);
+            provider.addProvider(new FilterSubprovider());
+            const rpcSubproviders = _.map(configs.PUBLIC_NODE_URLS_BY_NETWORK_ID[networkIdIfExists], publicNodeUrl => {
+                return new RpcSubprovider({
+                    rpcUrl: publicNodeUrl,
+                });
+            });
+            provider.addProvider(new RedundantSubprovider(rpcSubproviders as Subprovider[]));
+            provider.start();
+            return [provider, ledgerSubprovider];
+        } else if (doesInjectedWeb3Exist && isPublicNodeAvailableForNetworkId) {
             // We catch all requests involving a users account and send it to the injectedWeb3
             // instance. All other requests go to the public hosted node.
-            provider = new ProviderEngine();
+            const provider = new ProviderEngine();
             provider.addProvider(new InjectedWeb3Subprovider(injectedWeb3.currentProvider));
             provider.addProvider(new FilterSubprovider());
             const rpcSubproviders = _.map(publicNodeUrlsIfExistsForNetworkId, publicNodeUrl => {
@@ -111,16 +160,17 @@ export class Blockchain {
             });
             provider.addProvider(new RedundantSubprovider(rpcSubproviders as Subprovider[]));
             provider.start();
+            return [provider, undefined];
         } else if (doesInjectedWeb3Exist) {
             // Since no public node for this network, all requests go to injectedWeb3 instance
-            provider = injectedWeb3.currentProvider;
+            return [injectedWeb3.currentProvider, undefined];
         } else {
             // If no injectedWeb3 instance, all requests fallback to our public hosted mainnet/testnet node
             // We do this so that users can still browse the 0x Portal DApp even if they do not have web3
             // injected into their browser.
-            provider = new ProviderEngine();
+            const provider = new ProviderEngine();
             provider.addProvider(new FilterSubprovider());
-            const networkId = configs.IS_MAINNET_ENABLED ? constants.NETWORK_ID_MAINNET : constants.NETWORK_ID_KOVAN;
+            const networkId = constants.NETWORK_ID_MAINNET;
             const rpcSubproviders = _.map(configs.PUBLIC_NODE_URLS_BY_NETWORK_ID[networkId], publicNodeUrl => {
                 return new RpcSubprovider({
                     rpcUrl: publicNodeUrl,
@@ -128,14 +178,15 @@ export class Blockchain {
             });
             provider.addProvider(new RedundantSubprovider(rpcSubproviders as Subprovider[]));
             provider.start();
+            return [provider, undefined];
         }
-
-        return provider;
     }
     constructor(dispatcher: Dispatcher) {
         this._dispatcher = dispatcher;
         const defaultGasPrice = GWEI_IN_WEI * 30;
         this._defaultGasPrice = new BigNumber(defaultGasPrice);
+        // We need a unique reference to this function so we can use it to unsubcribe.
+        this._injectedProviderUpdateHandler = this._handleInjectedProviderUpdateAsync.bind(this);
         // tslint:disable-next-line:no-floating-promises
         this._updateDefaultGasPriceAsync();
         // tslint:disable-next-line:no-floating-promises
@@ -185,84 +236,17 @@ export class Blockchain {
         this._ledgerSubprovider.setPath(path);
     }
     public async updateProviderToLedgerAsync(networkId: number): Promise<void> {
-        utils.assert(!_.isUndefined(this._contractWrappers), 'Contract Wrappers must be instantiated.');
-
-        const isU2FSupported = await utils.isU2FSupportedAsync();
-        if (!isU2FSupported) {
-            throw new Error('Cannot update providerType to LEDGER without U2F support');
-        }
-
-        // Cache injected provider so that we can switch the user back to it easily
-        if (_.isUndefined(this._cachedProvider)) {
-            this._cachedProvider = this._web3Wrapper.getProvider();
-            this._cachedProviderNetworkId = this.networkId;
-        }
-
-        this._blockchainWatcher.destroy();
-
-        delete this._userAddressIfExists;
-        this._dispatcher.updateUserAddress(undefined); // Clear old userAddress
-
-        const provider = new ProviderEngine();
-        const ledgerWalletConfigs = {
-            networkId,
-            ledgerEthereumClientFactoryAsync: ledgerEthereumBrowserClientFactoryAsync,
-        };
-        this._ledgerSubprovider = new LedgerSubprovider(ledgerWalletConfigs);
-        provider.addProvider(this._ledgerSubprovider);
-        provider.addProvider(new FilterSubprovider());
-        const rpcSubproviders = _.map(configs.PUBLIC_NODE_URLS_BY_NETWORK_ID[networkId], publicNodeUrl => {
-            return new RpcSubprovider({
-                rpcUrl: publicNodeUrl,
-            });
-        });
-        provider.addProvider(new RedundantSubprovider(rpcSubproviders as Subprovider[]));
-        provider.start();
-        this.networkId = networkId;
-        this._dispatcher.updateNetworkId(this.networkId);
         const shouldPollUserAddress = false;
-        this._web3Wrapper = new Web3Wrapper(provider);
-        this._blockchainWatcher = new BlockchainWatcher(
-            this._dispatcher,
-            this._web3Wrapper,
-            this.networkId,
-            shouldPollUserAddress,
-        );
-        this._contractWrappers.setProvider(provider, this.networkId);
-        await this._blockchainWatcher.startEmittingNetworkConnectionAndUserBalanceStateAsync();
-        this._dispatcher.updateProviderType(ProviderType.Ledger);
+        const shouldUserLedgerProvider = true;
+        await this._resetOrInitializeAsync(networkId, shouldPollUserAddress, shouldUserLedgerProvider);
     }
     public async updateProviderToInjectedAsync(): Promise<void> {
-        utils.assert(!_.isUndefined(this._contractWrappers), 'Contract Wrappers must be instantiated.');
-
-        if (_.isUndefined(this._cachedProvider)) {
-            return; // Going from injected to injected, so we noop
-        }
-
-        this._blockchainWatcher.destroy();
-
-        const provider = this._cachedProvider;
-        this.networkId = this._cachedProviderNetworkId;
-
         const shouldPollUserAddress = true;
-        this._web3Wrapper = new Web3Wrapper(provider);
-        this._blockchainWatcher = new BlockchainWatcher(
-            this._dispatcher,
-            this._web3Wrapper,
-            this.networkId,
-            shouldPollUserAddress,
-        );
-
-        const userAddresses = await this._web3Wrapper.getAvailableAddressesAsync();
-        this._userAddressIfExists = userAddresses[0];
-
-        this._contractWrappers.setProvider(provider, this.networkId);
-
-        await this.fetchTokenInformationAsync();
-        await this._blockchainWatcher.startEmittingNetworkConnectionAndUserBalanceStateAsync();
-        this._dispatcher.updateProviderType(ProviderType.Injected);
-        delete this._ledgerSubprovider;
-        delete this._cachedProvider;
+        const shouldUserLedgerProvider = false;
+        this._dispatcher.updateBlockchainIsLoaded(false);
+        // We don't want to be out of sync with the network the injected provider declares.
+        const networkId = await Blockchain._getInjectedWeb3ProviderNetworkIdIfExistsAsync();
+        await this._resetOrInitializeAsync(networkId, shouldPollUserAddress, shouldUserLedgerProvider);
     }
     public async setProxyAllowanceAsync(token: Token, amountInBaseUnits: BigNumber): Promise<void> {
         utils.assert(this.isValidAddress(token.address), BlockchainCallErrs.TokenAddressIsInvalid);
@@ -538,6 +522,7 @@ export class Blockchain {
     }
     public destroy(): void {
         this._blockchainWatcher.destroy();
+        this._injectedProviderObservable.unsubscribe(this._injectedProviderUpdateHandler);
         this._stopWatchingExchangeLogFillEvents();
     }
     public async fetchTokenInformationAsync(): Promise<void> {
@@ -559,6 +544,7 @@ export class Blockchain {
             tokenRegistryTokenSymbols,
             configs.DEFAULT_TRACKED_TOKEN_SYMBOLS,
         );
+        const currentTimestamp = moment().unix();
         if (defaultTrackedTokensInRegistry.length !== configs.DEFAULT_TRACKED_TOKEN_SYMBOLS.length) {
             this._dispatcher.updateShouldBlockchainErrDialogBeOpen(true);
             this._dispatcher.encounteredBlockchainError(BlockchainErrs.DefaultTokensNotInTokenRegistry);
@@ -573,7 +559,7 @@ export class Blockchain {
         if (_.isEmpty(trackedTokensByAddress)) {
             _.each(configs.DEFAULT_TRACKED_TOKEN_SYMBOLS, symbol => {
                 const token = _.find(tokenRegistryTokens, t => t.symbol === symbol);
-                token.isTracked = true;
+                token.trackedTimestamp = currentTimestamp;
                 trackedTokensByAddress[token.address] = token;
             });
             if (!_.isUndefined(this._userAddressIfExists)) {
@@ -582,10 +568,10 @@ export class Blockchain {
                 });
             }
         } else {
-            // Properly set all tokenRegistry tokens `isTracked` to true if they are in the existing trackedTokens array
-            _.each(trackedTokensByAddress, (_trackedToken: Token, address: string) => {
+            // Properly set all tokenRegistry tokens `trackedTimestamp` if they are in the existing trackedTokens array
+            _.each(trackedTokensByAddress, (trackedToken: Token, address: string) => {
                 if (!_.isUndefined(tokenRegistryTokensByAddress[address])) {
-                    tokenRegistryTokensByAddress[address].isTracked = true;
+                    tokenRegistryTokensByAddress[address].trackedTimestamp = trackedToken.trackedTimestamp;
                 }
             });
         }
@@ -632,6 +618,18 @@ export class Blockchain {
     private _doesUserAddressExist(): boolean {
         return !_.isUndefined(this._userAddressIfExists);
     }
+    private async _handleInjectedProviderUpdateAsync(update: InjectedProviderUpdate): Promise<void> {
+        if (update.networkVersion === 'loading' || !_.isUndefined(this._ledgerSubprovider)) {
+            return;
+        }
+        const updatedNetworkId = _.parseInt(update.networkVersion);
+        if (this.networkId === updatedNetworkId) {
+            return;
+        }
+        const shouldPollUserAddress = true;
+        const shouldUserLedgerProvider = false;
+        await this._resetOrInitializeAsync(updatedNetworkId, shouldPollUserAddress, shouldUserLedgerProvider);
+    }
     private async _rehydrateStoreWithContractEventsAsync(): Promise<void> {
         // Ensure we are only ever listening to one set of events
         this._stopWatchingExchangeLogFillEvents();
@@ -765,7 +763,7 @@ export class Blockchain {
                 name: t.name,
                 symbol: t.symbol,
                 decimals: t.decimals,
-                isTracked: false,
+                trackedTimestamp: undefined,
                 isRegistered: true,
             };
             tokenByAddress[token.address] = token;
@@ -774,49 +772,64 @@ export class Blockchain {
     }
     private async _onPageLoadInitFireAndForgetAsync(): Promise<void> {
         await utils.onPageLoadAsync(); // wait for page to load
-
-        // Hack: We need to know the networkId the injectedWeb3 is connected to (if it is defined) in
-        // order to properly instantiate the web3Wrapper. Since we must use the async call, we cannot
-        // retrieve it from within the web3Wrapper constructor. This is and should remain the only
-        // call to a web3 instance outside of web3Wrapper in the entire dapp.
-        // In addition, if the user has an injectedWeb3 instance that is disconnected from a backing
-        // Ethereum node, this call will throw. We need to handle this case gracefully
-        const injectedWeb3 = (window as any).web3;
-        let networkIdIfExists: number;
-        if (!_.isUndefined(injectedWeb3)) {
-            try {
-                networkIdIfExists = _.parseInt(await promisify<string>(injectedWeb3.version.getNetwork)());
-            } catch (err) {
-                // Ignore error and proceed with networkId undefined
+        const networkIdIfExists = await Blockchain._getInjectedWeb3ProviderNetworkIdIfExistsAsync();
+        this.networkId = !_.isUndefined(networkIdIfExists) ? networkIdIfExists : constants.NETWORK_ID_MAINNET;
+        const injectedWeb3IfExists = Blockchain._getInjectedWeb3();
+        if (!_.isUndefined(injectedWeb3IfExists) && !_.isUndefined(injectedWeb3IfExists.currentProvider)) {
+            const injectedProviderObservable = injectedWeb3IfExists.currentProvider.publicConfigStore;
+            if (!_.isUndefined(injectedProviderObservable) && _.isUndefined(this._injectedProviderObservable)) {
+                this._injectedProviderObservable = injectedProviderObservable;
+                this._injectedProviderObservable.subscribe(this._injectedProviderUpdateHandler);
             }
         }
-
-        const provider = await Blockchain._getProviderAsync(injectedWeb3, networkIdIfExists);
-        this.networkId = !_.isUndefined(networkIdIfExists)
-            ? networkIdIfExists
-            : configs.IS_MAINNET_ENABLED
-                ? constants.NETWORK_ID_MAINNET
-                : constants.NETWORK_ID_KOVAN;
-        this._dispatcher.updateNetworkId(this.networkId);
-        const zeroExConfigs = {
-            networkId: this.networkId,
-        };
-        this._contractWrappers = new ContractWrappers(provider, zeroExConfigs);
-        this._updateProviderName(injectedWeb3);
+        this._updateProviderName(injectedWeb3IfExists);
         const shouldPollUserAddress = true;
-        this._web3Wrapper = new Web3Wrapper(provider);
-        this._blockchainWatcher = new BlockchainWatcher(
-            this._dispatcher,
-            this._web3Wrapper,
-            this.networkId,
-            shouldPollUserAddress,
+        const shouldUseLedgerProvider = false;
+        await this._resetOrInitializeAsync(this.networkId, shouldPollUserAddress, shouldUseLedgerProvider);
+    }
+    private async _resetOrInitializeAsync(
+        networkId: number,
+        shouldPollUserAddress: boolean = false,
+        shouldUserLedgerProvider: boolean = false,
+    ): Promise<void> {
+        if (!shouldUserLedgerProvider) {
+            this._dispatcher.updateBlockchainIsLoaded(false);
+        }
+        this._dispatcher.updateUserWeiBalance(undefined);
+        this.networkId = networkId;
+        const injectedWeb3IfExists = Blockchain._getInjectedWeb3();
+        const [provider, ledgerSubproviderIfExists] = await Blockchain._getProviderAsync(
+            injectedWeb3IfExists,
+            networkId,
+            shouldUserLedgerProvider,
         );
-
-        const userAddresses = await this._web3Wrapper.getAvailableAddressesAsync();
-        this._userAddressIfExists = userAddresses[0];
-        this._dispatcher.updateUserAddress(this._userAddressIfExists);
-        await this.fetchTokenInformationAsync();
-        await this._blockchainWatcher.startEmittingNetworkConnectionAndUserBalanceStateAsync();
+        if (!_.isUndefined(this._contractWrappers)) {
+            this._contractWrappers.setProvider(provider, networkId);
+        } else {
+            this._contractWrappers = new ContractWrappers(provider, { networkId });
+        }
+        if (!_.isUndefined(this._blockchainWatcher)) {
+            this._blockchainWatcher.destroy();
+        }
+        this._web3Wrapper = new Web3Wrapper(provider);
+        this._blockchainWatcher = new BlockchainWatcher(this._dispatcher, this._web3Wrapper, shouldPollUserAddress);
+        if (shouldUserLedgerProvider && !_.isUndefined(ledgerSubproviderIfExists)) {
+            delete this._userAddressIfExists;
+            this._ledgerSubprovider = ledgerSubproviderIfExists;
+            this._dispatcher.updateUserAddress(undefined);
+            this._dispatcher.updateProviderType(ProviderType.Ledger);
+        } else {
+            delete this._ledgerSubprovider;
+            const userAddresses = await this._web3Wrapper.getAvailableAddressesAsync();
+            this._userAddressIfExists = userAddresses[0];
+            this._dispatcher.updateUserAddress(this._userAddressIfExists);
+            if (!_.isUndefined(injectedWeb3IfExists)) {
+                this._dispatcher.updateProviderType(ProviderType.Injected);
+            }
+            await this.fetchTokenInformationAsync();
+        }
+        await this._blockchainWatcher.startEmittingUserBalanceStateAsync();
+        this._dispatcher.updateNetworkId(networkId);
         await this._rehydrateStoreWithContractEventsAsync();
     }
     private _updateProviderName(injectedWeb3: Web3): void {
diff --git a/packages/website/ts/blockchain_watcher.ts b/packages/website/ts/blockchain_watcher.ts
index c576db6ac..df5f73fd1 100644
--- a/packages/website/ts/blockchain_watcher.ts
+++ b/packages/website/ts/blockchain_watcher.ts
@@ -6,24 +6,17 @@ import { Dispatcher } from 'ts/redux/dispatcher';
 export class BlockchainWatcher {
     private _dispatcher: Dispatcher;
     private _web3Wrapper: Web3Wrapper;
-    private _prevNetworkId: number;
     private _shouldPollUserAddress: boolean;
-    private _watchNetworkAndBalanceIntervalId: NodeJS.Timer;
+    private _watchBalanceIntervalId: NodeJS.Timer;
     private _prevUserEtherBalanceInWei?: BigNumber;
     private _prevUserAddressIfExists: string;
-    constructor(
-        dispatcher: Dispatcher,
-        web3Wrapper: Web3Wrapper,
-        networkIdIfExists: number,
-        shouldPollUserAddress: boolean,
-    ) {
+    constructor(dispatcher: Dispatcher, web3Wrapper: Web3Wrapper, shouldPollUserAddress: boolean) {
         this._dispatcher = dispatcher;
-        this._prevNetworkId = networkIdIfExists;
         this._shouldPollUserAddress = shouldPollUserAddress;
         this._web3Wrapper = web3Wrapper;
     }
     public destroy(): void {
-        this._stopEmittingNetworkConnectionAndUserBalanceState();
+        this._stopEmittingUserBalanceState();
         // HACK: stop() is only available on providerEngine instances
         const provider = this._web3Wrapper.getProvider();
         if (!_.isUndefined((provider as any).stop)) {
@@ -34,36 +27,23 @@ export class BlockchainWatcher {
     public updatePrevUserAddress(userAddress: string): void {
         this._prevUserAddressIfExists = userAddress;
     }
-    public async startEmittingNetworkConnectionAndUserBalanceStateAsync(): Promise<void> {
-        if (!_.isUndefined(this._watchNetworkAndBalanceIntervalId)) {
+    public async startEmittingUserBalanceStateAsync(): Promise<void> {
+        if (!_.isUndefined(this._watchBalanceIntervalId)) {
             return; // we are already emitting the state
         }
         this._prevUserEtherBalanceInWei = undefined;
-        this._dispatcher.updateNetworkId(this._prevNetworkId);
-        await this._updateNetworkAndBalanceAsync();
-        this._watchNetworkAndBalanceIntervalId = intervalUtils.setAsyncExcludingInterval(
-            this._updateNetworkAndBalanceAsync.bind(this),
+        await this._updateBalanceAsync();
+        this._watchBalanceIntervalId = intervalUtils.setAsyncExcludingInterval(
+            this._updateBalanceAsync.bind(this),
             5000,
             (err: Error) => {
                 logUtils.log(`Watching network and balances failed: ${err.stack}`);
-                this._stopEmittingNetworkConnectionAndUserBalanceState();
+                this._stopEmittingUserBalanceState();
             },
         );
     }
-    private async _updateNetworkAndBalanceAsync(): Promise<void> {
-        // Check for network state changes
+    private async _updateBalanceAsync(): Promise<void> {
         let prevNodeVersion: string;
-        let currentNetworkId;
-        try {
-            currentNetworkId = await this._web3Wrapper.getNetworkIdAsync();
-        } catch (err) {
-            // Noop
-        }
-        if (currentNetworkId !== this._prevNetworkId) {
-            this._prevNetworkId = currentNetworkId;
-            this._dispatcher.updateNetworkId(currentNetworkId);
-        }
-
         // Check for node version changes
         const currentNodeVersion = await this._web3Wrapper.getNodeVersionAsync();
         if (currentNodeVersion !== prevNodeVersion) {
@@ -99,9 +79,9 @@ export class BlockchainWatcher {
             this._dispatcher.updateUserWeiBalance(balanceInWei);
         }
     }
-    private _stopEmittingNetworkConnectionAndUserBalanceState(): void {
-        if (!_.isUndefined(this._watchNetworkAndBalanceIntervalId)) {
-            intervalUtils.clearAsyncExcludingInterval(this._watchNetworkAndBalanceIntervalId);
+    private _stopEmittingUserBalanceState(): void {
+        if (!_.isUndefined(this._watchBalanceIntervalId)) {
+            intervalUtils.clearAsyncExcludingInterval(this._watchBalanceIntervalId);
         }
     }
 }
diff --git a/packages/website/ts/components/dialogs/blockchain_err_dialog.tsx b/packages/website/ts/components/dialogs/blockchain_err_dialog.tsx
index b968a3147..c8e10303f 100644
--- a/packages/website/ts/components/dialogs/blockchain_err_dialog.tsx
+++ b/packages/website/ts/components/dialogs/blockchain_err_dialog.tsx
@@ -4,7 +4,6 @@ import FlatButton from 'material-ui/FlatButton';
 import * as React from 'react';
 import { Blockchain } from 'ts/blockchain';
 import { BlockchainErrs } from 'ts/types';
-import { configs } from 'ts/utils/configs';
 import { constants } from 'ts/utils/constants';
 
 interface BlockchainErrDialogProps {
@@ -125,8 +124,7 @@ export class BlockchainErrDialog extends React.Component<BlockchainErrDialogProp
                         Parity Signer Chrome extension
                     </a>{' '}
                     lets you connect to a locally running Parity node. Make sure you have started your local Parity node
-                    with {configs.IS_MAINNET_ENABLED && '`parity ui` or'} `parity --chain kovan ui` in order to connect
-                    to {configs.IS_MAINNET_ENABLED ? 'mainnet or Kovan respectively.' : 'Kovan.'}
+                    with `parity ui` or `parity --chain kovan ui` in order to connect to mainnet or Kovan respectively.
                 </div>
                 <div className="pt2">
                     <span className="bold">Note:</span> If you have done one of the above steps and are still seeing
@@ -142,10 +140,8 @@ export class BlockchainErrDialog extends React.Component<BlockchainErrDialogProp
                 <div>
                     The 0x smart contracts are not deployed on the Ethereum network you are currently connected to
                     (network Id: {this.props.networkId}). In order to use the 0x portal dApp, please connect to the{' '}
-                    {Networks.Kovan} testnet (network Id: {constants.NETWORK_ID_KOVAN})
-                    {configs.IS_MAINNET_ENABLED
-                        ? ` or ${constants.MAINNET_NAME} (network Id: ${constants.NETWORK_ID_MAINNET}).`
-                        : `.`}
+                    {Networks.Kovan} testnet (network Id: {constants.NETWORK_ID_KOVAN}) or ${constants.MAINNET_NAME}{' '}
+                    (network Id: ${constants.NETWORK_ID_MAINNET}).
                 </div>
                 <h4>Metamask</h4>
                 <div>
@@ -159,11 +155,8 @@ export class BlockchainErrDialog extends React.Component<BlockchainErrDialogProp
                     If using the{' '}
                     <a href={constants.URL_PARITY_CHROME_STORE} target="_blank">
                         Parity Signer Chrome extension
-                    </a>, make sure to start your local Parity node with{' '}
-                    {configs.IS_MAINNET_ENABLED
-                        ? '`parity ui` or `parity --chain Kovan ui` in order to connect to mainnet \
-                         or Kovan respectively.'
-                        : '`parity --chain kovan ui` in order to connect to Kovan.'}
+                    </a>, make sure to start your local Parity node with `parity ui` or `parity --chain Kovan ui` in
+                    order to connect to mainnet \ or Kovan respectively.
                 </div>
             </div>
         );
diff --git a/packages/website/ts/components/dialogs/ledger_config_dialog.tsx b/packages/website/ts/components/dialogs/ledger_config_dialog.tsx
index c9727b553..38e4732a4 100644
--- a/packages/website/ts/components/dialogs/ledger_config_dialog.tsx
+++ b/packages/website/ts/components/dialogs/ledger_config_dialog.tsx
@@ -282,6 +282,7 @@ export class LedgerConfigDialog extends React.Component<LedgerConfigDialogProps,
         if (didSucceed) {
             this.setState({
                 stepIndex: LedgerSteps.SELECT_ADDRESS,
+                connectionErrMsg: '',
             });
         }
         return didSucceed;
diff --git a/packages/website/ts/components/dialogs/track_token_confirmation_dialog.tsx b/packages/website/ts/components/dialogs/track_token_confirmation_dialog.tsx
index f6594b9d5..3751ce06f 100644
--- a/packages/website/ts/components/dialogs/track_token_confirmation_dialog.tsx
+++ b/packages/website/ts/components/dialogs/track_token_confirmation_dialog.tsx
@@ -1,5 +1,6 @@
 import Dialog from 'material-ui/Dialog';
 import FlatButton from 'material-ui/FlatButton';
+import * as moment from 'moment';
 import * as React from 'react';
 import { Blockchain } from 'ts/blockchain';
 import { TrackTokenConfirmation } from 'ts/components/track_token_confirmation';
@@ -73,12 +74,13 @@ export class TrackTokenConfirmationDialog extends React.Component<
         this.setState({
             isAddingTokenToTracked: true,
         });
+        const currentTimestamp = moment().unix();
         for (const token of this.props.tokens) {
             const newTokenEntry = {
                 ...token,
+                trackedTimestamp: currentTimestamp,
             };
 
-            newTokenEntry.isTracked = true;
             trackedTokenStorage.addTrackedTokenToUser(this.props.userAddress, this.props.networkId, newTokenEntry);
             this.props.dispatcher.updateTokenByAddress([newTokenEntry]);
         }
diff --git a/packages/website/ts/components/fill_order.tsx b/packages/website/ts/components/fill_order.tsx
index f3ea44286..03ba1183d 100644
--- a/packages/website/ts/components/fill_order.tsx
+++ b/packages/website/ts/components/fill_order.tsx
@@ -373,26 +373,26 @@ export class FillOrder extends React.Component<FillOrderProps, FillOrderState> {
 
         const tokensToTrack: Token[] = [];
         const isUnseenMakerToken = _.isUndefined(makerTokenIfExists);
-        const isMakerTokenTracked = !_.isUndefined(makerTokenIfExists) && makerTokenIfExists.isTracked;
+        const isMakerTokenTracked = !_.isUndefined(makerTokenIfExists) && utils.isTokenTracked(makerTokenIfExists);
         if (isUnseenMakerToken) {
             tokensToTrack.push({
                 ...this.state.parsedOrder.metadata.makerToken,
                 address: this.state.parsedOrder.signedOrder.makerTokenAddress,
                 iconUrl: undefined,
-                isTracked: false,
+                trackedTimestamp: undefined,
                 isRegistered: false,
             });
         } else if (!isMakerTokenTracked) {
             tokensToTrack.push(makerTokenIfExists);
         }
         const isUnseenTakerToken = _.isUndefined(takerTokenIfExists);
-        const isTakerTokenTracked = !_.isUndefined(takerTokenIfExists) && takerTokenIfExists.isTracked;
+        const isTakerTokenTracked = !_.isUndefined(takerTokenIfExists) && utils.isTokenTracked(takerTokenIfExists);
         if (isUnseenTakerToken) {
             tokensToTrack.push({
                 ...this.state.parsedOrder.metadata.takerToken,
                 address: this.state.parsedOrder.signedOrder.takerTokenAddress,
                 iconUrl: undefined,
-                isTracked: false,
+                trackedTimestamp: undefined,
                 isRegistered: false,
             });
         } else if (!isTakerTokenTracked) {
diff --git a/packages/website/ts/components/generate_order/asset_picker.tsx b/packages/website/ts/components/generate_order/asset_picker.tsx
index 0f569e1ad..3d53a9e7d 100644
--- a/packages/website/ts/components/generate_order/asset_picker.tsx
+++ b/packages/website/ts/components/generate_order/asset_picker.tsx
@@ -1,6 +1,7 @@
 import * as _ from 'lodash';
 import Dialog from 'material-ui/Dialog';
 import FlatButton from 'material-ui/FlatButton';
+import * as moment from 'moment';
 import * as React from 'react';
 import { Blockchain } from 'ts/blockchain';
 import { NewTokenForm } from 'ts/components/generate_order/new_token_form';
@@ -10,6 +11,7 @@ import { trackedTokenStorage } from 'ts/local_storage/tracked_token_storage';
 import { Dispatcher } from 'ts/redux/dispatcher';
 import { DialogConfigs, Token, TokenByAddress, TokenVisibility } from 'ts/types';
 import { constants } from 'ts/utils/constants';
+import { utils } from 'ts/utils/utils';
 
 const TOKEN_ICON_DIMENSION = 100;
 const TILE_DIMENSION = 146;
@@ -134,8 +136,8 @@ export class AssetPicker extends React.Component<AssetPickerProps, AssetPickerSt
         let tileStyles;
         const gridTiles = _.map(this.props.tokenByAddress, (token: Token, address: string) => {
             if (
-                (this.props.tokenVisibility === TokenVisibility.TRACKED && !token.isTracked) ||
-                (this.props.tokenVisibility === TokenVisibility.UNTRACKED && token.isTracked) ||
+                (this.props.tokenVisibility === TokenVisibility.TRACKED && !utils.isTokenTracked(token)) ||
+                (this.props.tokenVisibility === TokenVisibility.UNTRACKED && utils.isTokenTracked(token)) ||
                 token.symbol === constants.ZRX_TOKEN_SYMBOL ||
                 token.symbol === constants.ETHER_TOKEN_SYMBOL
             ) {
@@ -212,7 +214,7 @@ export class AssetPicker extends React.Component<AssetPickerProps, AssetPickerSt
     }
     private _onChooseToken(tokenAddress: string): void {
         const token = this.props.tokenByAddress[tokenAddress];
-        if (token.isTracked) {
+        if (utils.isTokenTracked(token)) {
             this.props.onTokenChosen(tokenAddress);
         } else {
             this.setState({
@@ -257,9 +259,8 @@ export class AssetPicker extends React.Component<AssetPickerProps, AssetPickerSt
         }
         const newTokenEntry = {
             ...token,
+            trackedTimestamp: moment().unix(),
         };
-
-        newTokenEntry.isTracked = true;
         trackedTokenStorage.addTrackedTokenToUser(this.props.userAddress, this.props.networkId, newTokenEntry);
 
         this.props.dispatcher.updateTokenByAddress([newTokenEntry]);
diff --git a/packages/website/ts/components/generate_order/new_token_form.tsx b/packages/website/ts/components/generate_order/new_token_form.tsx
index 176a0807b..3d7eda84c 100644
--- a/packages/website/ts/components/generate_order/new_token_form.tsx
+++ b/packages/website/ts/components/generate_order/new_token_form.tsx
@@ -1,6 +1,7 @@
 import { colors } from '@0xproject/react-shared';
 import * as _ from 'lodash';
 import TextField from 'material-ui/TextField';
+import * as moment from 'moment';
 import * as React from 'react';
 import { Blockchain } from 'ts/blockchain';
 import { AddressInput } from 'ts/components/inputs/address_input';
@@ -147,7 +148,7 @@ export class NewTokenForm extends React.Component<NewTokenFormProps, NewTokenFor
             iconUrl: undefined,
             name: this.state.name,
             symbol: this.state.symbol.toUpperCase(),
-            isTracked: true,
+            trackedTimestamp: moment().unix(),
             isRegistered: false,
         };
         this.props.onNewTokenSubmitted(newToken);
diff --git a/packages/website/ts/components/legacy_portal/legacy_portal.tsx b/packages/website/ts/components/legacy_portal/legacy_portal.tsx
index b4a174a03..c85d97207 100644
--- a/packages/website/ts/components/legacy_portal/legacy_portal.tsx
+++ b/packages/website/ts/components/legacy_portal/legacy_portal.tsx
@@ -23,7 +23,6 @@ import { GenerateOrderForm } from 'ts/containers/generate_order_form';
 import { localStorage } from 'ts/local_storage/local_storage';
 import { Dispatcher } from 'ts/redux/dispatcher';
 import { BlockchainErrs, HashData, Order, ProviderType, ScreenWidths, TokenByAddress, WebsitePaths } from 'ts/types';
-import { configs } from 'ts/utils/configs';
 import { constants } from 'ts/utils/constants';
 import { orderParser } from 'ts/utils/order_parser';
 import { Translate } from 'ts/utils/translate';
@@ -170,67 +169,53 @@ export class LegacyPortal extends React.Component<LegacyPortalProps, LegacyPorta
                 />
                 <div id="portal" className="mx-auto max-width-4" style={{ width: '100%' }}>
                     <Paper className="mb3 mt2">
-                        {!configs.IS_MAINNET_ENABLED && this.props.networkId === constants.NETWORK_ID_MAINNET ? (
-                            <div className="p3 center">
-                                <div className="h2 py2">Mainnet unavailable</div>
-                                <div className="mx-auto pb2 pt2">
-                                    <img src="/images/zrx_token.png" style={{ width: 150 }} />
-                                </div>
-                                <div>
-                                    0x portal is currently unavailable on the Ethereum mainnet.
-                                    <div>To try it out, switch to the Kovan test network (networkId: 42).</div>
-                                    <div className="py2">Check back soon!</div>
-                                </div>
+                        <div className="mx-auto flex">
+                            <div className="col col-2 pr2 pt1 sm-hide xs-hide" style={portalMenuContainerStyle}>
+                                <LegacyPortalMenu menuItemStyle={{ color: colors.white }} />
                             </div>
-                        ) : (
-                            <div className="mx-auto flex">
-                                <div className="col col-2 pr2 pt1 sm-hide xs-hide" style={portalMenuContainerStyle}>
-                                    <LegacyPortalMenu menuItemStyle={{ color: colors.white }} />
-                                </div>
-                                <div className="col col-12 lg-col-10 md-col-10 sm-col sm-col-12">
-                                    <div className="py2" style={{ backgroundColor: colors.grey50 }}>
-                                        {this.props.blockchainIsLoaded ? (
-                                            <Switch>
-                                                <Route
-                                                    path={`${WebsitePaths.Portal}/weth`}
-                                                    render={this._renderEthWrapper.bind(this)}
-                                                />
-                                                <Route
-                                                    path={`${WebsitePaths.Portal}/fill`}
-                                                    render={this._renderFillOrder.bind(this)}
-                                                />
-                                                <Route
-                                                    path={`${WebsitePaths.Portal}/balances`}
-                                                    render={this._renderTokenBalances.bind(this)}
-                                                />
-                                                <Route
-                                                    path={`${WebsitePaths.Portal}/trades`}
-                                                    render={this._renderTradeHistory.bind(this)}
-                                                />
-                                                <Route
-                                                    path={`${WebsitePaths.Home}`}
-                                                    render={this._renderGenerateOrderForm.bind(this)}
-                                                />
-                                            </Switch>
-                                        ) : (
-                                            <div className="pt4 sm-px2 sm-pt2 sm-m1" style={{ height: 500 }}>
-                                                <div
-                                                    className="relative sm-px2 sm-pt2 sm-m1"
-                                                    style={{ height: 122, top: '50%', transform: 'translateY(-50%)' }}
-                                                >
-                                                    <div className="center pb2">
-                                                        <CircularProgress size={40} thickness={5} />
-                                                    </div>
-                                                    <div className="center pt2" style={{ paddingBottom: 11 }}>
-                                                        Loading Portal...
-                                                    </div>
+                            <div className="col col-12 lg-col-10 md-col-10 sm-col sm-col-12">
+                                <div className="py2" style={{ backgroundColor: colors.grey50 }}>
+                                    {this.props.blockchainIsLoaded ? (
+                                        <Switch>
+                                            <Route
+                                                path={`${WebsitePaths.Portal}/weth`}
+                                                render={this._renderEthWrapper.bind(this)}
+                                            />
+                                            <Route
+                                                path={`${WebsitePaths.Portal}/fill`}
+                                                render={this._renderFillOrder.bind(this)}
+                                            />
+                                            <Route
+                                                path={`${WebsitePaths.Portal}/balances`}
+                                                render={this._renderTokenBalances.bind(this)}
+                                            />
+                                            <Route
+                                                path={`${WebsitePaths.Portal}/trades`}
+                                                render={this._renderTradeHistory.bind(this)}
+                                            />
+                                            <Route
+                                                path={`${WebsitePaths.Home}`}
+                                                render={this._renderGenerateOrderForm.bind(this)}
+                                            />
+                                        </Switch>
+                                    ) : (
+                                        <div className="pt4 sm-px2 sm-pt2 sm-m1" style={{ height: 500 }}>
+                                            <div
+                                                className="relative sm-px2 sm-pt2 sm-m1"
+                                                style={{ height: 122, top: '50%', transform: 'translateY(-50%)' }}
+                                            >
+                                                <div className="center pb2">
+                                                    <CircularProgress size={40} thickness={5} />
+                                                </div>
+                                                <div className="center pt2" style={{ paddingBottom: 11 }}>
+                                                    Loading Portal...
                                                 </div>
                                             </div>
-                                        )}
-                                    </div>
+                                        </div>
+                                    )}
                                 </div>
                             </div>
-                        )}
+                        </div>
                     </Paper>
                     <BlockchainErrDialog
                         blockchain={this._blockchain}
@@ -249,16 +234,14 @@ export class LegacyPortal extends React.Component<LegacyPortalProps, LegacyPorta
                         onToggleDialog={this._onPortalDisclaimerAccepted.bind(this)}
                     />
                     <FlashMessage dispatcher={this.props.dispatcher} flashMessage={this.props.flashMessage} />
-                    {this.props.blockchainIsLoaded && (
-                        <LedgerConfigDialog
-                            providerType={this.props.providerType}
-                            networkId={this.props.networkId}
-                            blockchain={this._blockchain}
-                            dispatcher={this.props.dispatcher}
-                            toggleDialogFn={this.onToggleLedgerDialog.bind(this)}
-                            isOpen={this.state.isLedgerDialogOpen}
-                        />
-                    )}
+                    <LedgerConfigDialog
+                        providerType={this.props.providerType}
+                        networkId={this.props.networkId}
+                        blockchain={this._blockchain}
+                        dispatcher={this.props.dispatcher}
+                        toggleDialogFn={this.onToggleLedgerDialog.bind(this)}
+                        isOpen={this.state.isLedgerDialogOpen}
+                    />
                 </div>
                 <Footer translate={this.props.translate} dispatcher={this.props.dispatcher} />
             </div>
@@ -292,8 +275,7 @@ export class LegacyPortal extends React.Component<LegacyPortalProps, LegacyPorta
         );
     }
     private _renderTokenBalances(): React.ReactNode {
-        const allTokens = _.values(this.props.tokenByAddress);
-        const trackedTokens = _.filter(allTokens, t => t.isTracked);
+        const trackedTokens = utils.getTrackedTokens(this.props.tokenByAddress);
         return (
             <TokenBalances
                 blockchain={this._blockchain}
diff --git a/packages/website/ts/components/onboarding/portal_onboarding_flow.tsx b/packages/website/ts/components/onboarding/portal_onboarding_flow.tsx
index 6486bafcb..1850a0966 100644
--- a/packages/website/ts/components/onboarding/portal_onboarding_flow.tsx
+++ b/packages/website/ts/components/onboarding/portal_onboarding_flow.tsx
@@ -186,9 +186,11 @@ class PlainPortalOnboardingFlow extends React.Component<PortalOnboardingFlowProp
         const ethToken = utils.getEthToken(this.props.tokenByAddress);
         const zrxToken = utils.getZrxToken(this.props.tokenByAddress);
         if (ethToken && zrxToken) {
-            const ethTokenAllowance = this.props.trackedTokenStateByAddress[ethToken.address].allowance;
-            const zrxTokenAllowance = this.props.trackedTokenStateByAddress[zrxToken.address].allowance;
-            return ethTokenAllowance > new BigNumber(0) && zrxTokenAllowance > new BigNumber(0);
+            const ethTokenState = this.props.trackedTokenStateByAddress[ethToken.address];
+            const zrxTokenState = this.props.trackedTokenStateByAddress[zrxToken.address];
+            if (ethTokenState && zrxTokenState) {
+                return ethTokenState.allowance.gt(0) && zrxTokenState.allowance.gt(0);
+            }
         }
         return false;
     }
@@ -251,12 +253,15 @@ class PlainPortalOnboardingFlow extends React.Component<PortalOnboardingFlowProp
         if (!token) {
             return null;
         }
-        const tokenState = this.props.trackedTokenStateByAddress[token.address];
+        const tokenStateIfExists = this.props.trackedTokenStateByAddress[token.address];
+        if (_.isUndefined(tokenStateIfExists)) {
+            return null;
+        }
         return (
             <AllowanceToggle
                 token={token}
-                tokenState={tokenState}
-                isDisabled={!tokenState.isLoaded}
+                tokenState={tokenStateIfExists}
+                isDisabled={!tokenStateIfExists.isLoaded}
                 blockchain={this.props.blockchain}
                 // tslint:disable-next-line:jsx-no-lambda
                 refetchTokenStateAsync={async () => this.props.refetchTokenStateAsync(token.address)}
diff --git a/packages/website/ts/components/portal/portal.tsx b/packages/website/ts/components/portal/portal.tsx
index 4166fde53..438c7b52f 100644
--- a/packages/website/ts/components/portal/portal.tsx
+++ b/packages/website/ts/components/portal/portal.tsx
@@ -152,9 +152,8 @@ export class Portal extends React.Component<PortalProps, PortalState> {
     }
     public componentDidUpdate(prevProps: PortalProps): void {
         if (!prevProps.blockchainIsLoaded && this.props.blockchainIsLoaded) {
-            const trackedTokenAddresses = _.keys(this.state.trackedTokenStateByAddress);
             // tslint:disable-next-line:no-floating-promises
-            this._fetchBalancesAndAllowancesAsync(trackedTokenAddresses);
+            this._fetchBalancesAndAllowancesAsync(this._getCurrentTrackedTokensAddresses());
         }
     }
     public componentWillReceiveProps(nextProps: PortalProps): void {
@@ -182,17 +181,17 @@ export class Portal extends React.Component<PortalProps, PortalState> {
                 prevPathname: nextProps.location.pathname,
             });
         }
+
+        // If the address changed, but the network did not, we can just refetch the currently tracked tokens.
         if (
-            nextProps.userAddress !== this.props.userAddress ||
-            nextProps.networkId !== this.props.networkId ||
+            (nextProps.userAddress !== this.props.userAddress && nextProps.networkId === this.props.networkId) ||
             nextProps.lastForceTokenStateRefetch !== this.props.lastForceTokenStateRefetch
         ) {
-            const trackedTokenAddresses = _.keys(this.state.trackedTokenStateByAddress);
             // tslint:disable-next-line:no-floating-promises
-            this._fetchBalancesAndAllowancesAsync(trackedTokenAddresses);
+            this._fetchBalancesAndAllowancesAsync(this._getCurrentTrackedTokensAddresses());
         }
 
-        const nextTrackedTokens = this._getTrackedTokens(nextProps.tokenByAddress);
+        const nextTrackedTokens = utils.getTrackedTokens(nextProps.tokenByAddress);
         const trackedTokens = this._getCurrentTrackedTokens();
 
         if (!_.isEqual(nextTrackedTokens, trackedTokens)) {
@@ -200,7 +199,7 @@ export class Portal extends React.Component<PortalProps, PortalState> {
             const newTokenAddresses = _.map(newTokens, token => token.address);
             // Add placeholder entry for this token to the state, since fetching the
             // balance/allowance is asynchronous
-            const trackedTokenStateByAddress = this.state.trackedTokenStateByAddress;
+            const trackedTokenStateByAddress = { ...this.state.trackedTokenStateByAddress };
             for (const tokenAddress of newTokenAddresses) {
                 trackedTokenStateByAddress[tokenAddress] = {
                     balance: new BigNumber(0),
@@ -265,16 +264,16 @@ export class Portal extends React.Component<PortalProps, PortalState> {
                         networkId={this.props.networkId}
                     />
                     <FlashMessage dispatcher={this.props.dispatcher} flashMessage={this.props.flashMessage} />
-                    {this.props.blockchainIsLoaded && (
-                        <LedgerConfigDialog
-                            providerType={this.props.providerType}
-                            networkId={this.props.networkId}
-                            blockchain={this._blockchain}
-                            dispatcher={this.props.dispatcher}
-                            toggleDialogFn={this._onToggleLedgerDialog.bind(this)}
-                            isOpen={this.state.isLedgerDialogOpen}
-                        />
-                    )}
+
+                    <LedgerConfigDialog
+                        providerType={this.props.providerType}
+                        networkId={this.props.networkId}
+                        blockchain={this._blockchain}
+                        dispatcher={this.props.dispatcher}
+                        toggleDialogFn={this._onToggleLedgerDialog.bind(this)}
+                        isOpen={this.state.isLedgerDialogOpen}
+                    />
+
                     <AssetPicker
                         userAddress={this.props.userAddress}
                         networkId={this.props.networkId}
@@ -563,9 +562,9 @@ export class Portal extends React.Component<PortalProps, PortalState> {
         if (this.state.tokenManagementState === TokenManagementState.Remove && !isDefaultTrackedToken) {
             if (token.isRegistered) {
                 // Remove the token from tracked tokens
-                const newToken = {
+                const newToken: Token = {
                     ...token,
-                    isTracked: false,
+                    trackedTimestamp: undefined,
                 };
                 this.props.dispatcher.updateTokenByAddress([newToken]);
             } else {
@@ -608,17 +607,12 @@ export class Portal extends React.Component<PortalProps, PortalState> {
         const isSmallScreen = this.props.screenWidth === ScreenWidths.Sm;
         return isSmallScreen;
     }
-
     private _getCurrentTrackedTokens(): Token[] {
-        return this._getTrackedTokens(this.props.tokenByAddress);
+        return utils.getTrackedTokens(this.props.tokenByAddress);
     }
-
-    private _getTrackedTokens(tokenByAddress: TokenByAddress): Token[] {
-        const allTokens = _.values(tokenByAddress);
-        const trackedTokens = _.filter(allTokens, t => t.isTracked);
-        return trackedTokens;
+    private _getCurrentTrackedTokensAddresses(): string[] {
+        return _.map(this._getCurrentTrackedTokens(), token => token.address);
     }
-
     private _getInitialTrackedTokenStateByAddress(trackedTokens: Token[]): TokenStateByAddress {
         const trackedTokenStateByAddress: TokenStateByAddress = {};
         _.each(trackedTokens, token => {
diff --git a/packages/website/ts/components/token_balances.tsx b/packages/website/ts/components/token_balances.tsx
index 7af80745c..3fae83c00 100644
--- a/packages/website/ts/components/token_balances.tsx
+++ b/packages/website/ts/components/token_balances.tsx
@@ -308,7 +308,7 @@ export class TokenBalances extends React.Component<TokenBalancesProps, TokenBala
         const trackedTokensStartingWithEtherToken = trackedTokens.sort(
             firstBy((t: Token) => t.symbol !== ETHER_TOKEN_SYMBOL)
                 .thenBy((t: Token) => t.symbol !== ZRX_TOKEN_SYMBOL)
-                .thenBy('address'),
+                .thenBy('trackedTimestamp'),
         );
         const tableRows = _.map(
             trackedTokensStartingWithEtherToken,
@@ -424,9 +424,9 @@ export class TokenBalances extends React.Component<TokenBalancesProps, TokenBala
         if (!this.state.isAddingToken && !isDefaultTrackedToken) {
             if (token.isRegistered) {
                 // Remove the token from tracked tokens
-                const newToken = {
+                const newToken: Token = {
                     ...token,
-                    isTracked: false,
+                    trackedTimestamp: undefined,
                 };
                 this.props.dispatcher.updateTokenByAddress([newToken]);
             } else {
diff --git a/packages/website/ts/components/top_bar/top_bar.tsx b/packages/website/ts/components/top_bar/top_bar.tsx
index 537edc7bb..fac6c131f 100644
--- a/packages/website/ts/components/top_bar/top_bar.tsx
+++ b/packages/website/ts/components/top_bar/top_bar.tsx
@@ -13,7 +13,6 @@ import { ProviderDisplay } from 'ts/components/top_bar/provider_display';
 import { TopBarMenuItem } from 'ts/components/top_bar/top_bar_menu_item';
 import { DropDown } from 'ts/components/ui/drop_down';
 import { Dispatcher } from 'ts/redux/dispatcher';
-import { zIndex } from 'ts/style/z_index';
 import { Deco, Key, ProviderType, WebsiteLegacyPaths, WebsitePaths } from 'ts/types';
 import { constants } from 'ts/utils/constants';
 import { Translate } from 'ts/utils/translate';
@@ -58,7 +57,6 @@ const styles: Styles = {
         width: '100%',
         position: 'relative',
         top: 0,
-        zIndex: zIndex.topBar,
         paddingBottom: 1,
     },
     bottomBar: {
diff --git a/packages/website/ts/components/wallet/wallet.tsx b/packages/website/ts/components/wallet/wallet.tsx
index 5dde0f4e7..e1a2d4ce7 100644
--- a/packages/website/ts/components/wallet/wallet.tsx
+++ b/packages/website/ts/components/wallet/wallet.tsx
@@ -156,6 +156,20 @@ export class Wallet extends React.Component<WalletProps, WalletState> {
             isHoveringSidebar: false,
         };
     }
+    public componentDidUpdate(prevProps: WalletProps): void {
+        const currentTrackedTokens = this.props.trackedTokens;
+        const differentTrackedTokens = _.difference(currentTrackedTokens, prevProps.trackedTokens);
+        const firstDifferentTrackedToken = _.head(differentTrackedTokens);
+        // check if there is only one different token, and if that token is a member of the current tracked tokens
+        // this means that the token was added, not removed
+        if (
+            !_.isUndefined(firstDifferentTrackedToken) &&
+            _.size(differentTrackedTokens) === 1 &&
+            _.includes(currentTrackedTokens, firstDifferentTrackedToken)
+        ) {
+            document.getElementById(firstDifferentTrackedToken.address).scrollIntoView();
+        }
+    }
     public render(): React.ReactNode {
         const isBlockchainLoaded = this.props.blockchainIsLoaded && this.props.blockchainErr === BlockchainErrs.NoError;
         return (
@@ -318,7 +332,7 @@ export class Wallet extends React.Component<WalletProps, WalletState> {
         const trackedTokensStartingWithEtherToken = trackedTokens.sort(
             firstBy((t: Token) => t.symbol !== constants.ETHER_TOKEN_SYMBOL)
                 .thenBy((t: Token) => t.symbol !== constants.ZRX_TOKEN_SYMBOL)
-                .thenBy('address'),
+                .thenBy('trackedTimestamp'),
         );
         return _.map(trackedTokensStartingWithEtherToken, this._renderTokenRow.bind(this));
     }
@@ -375,7 +389,7 @@ export class Wallet extends React.Component<WalletProps, WalletState> {
         const style = { ...styles.tokenItem, ...additionalStyle };
         const etherToken = this._getEthToken();
         return (
-            <div key={key} className={`flex flex-column ${className || ''}`}>
+            <div id={key} key={key} className={`flex flex-column ${className || ''}`}>
                 <StandardIconRow
                     icon={icon}
                     main={
diff --git a/packages/website/ts/index.tsx b/packages/website/ts/index.tsx
index 249b4fdc9..23387a95a 100644
--- a/packages/website/ts/index.tsx
+++ b/packages/website/ts/index.tsx
@@ -97,6 +97,7 @@ render(
                             <Route path={WebsitePaths.FAQ} component={FAQ as any} />
                             <Route path={WebsitePaths.About} component={About as any} />
                             <Route path={WebsitePaths.Wiki} component={Wiki as any} />
+                            <Route path={`${WebsitePaths.Docs}`} component={LazyZeroExJSDocumentation} />
                             <Route path={`${WebsitePaths.ZeroExJs}/:version?`} component={LazyZeroExJSDocumentation} />
                             <Route path={`${WebsitePaths.Connect}/:version?`} component={LazyConnectDocumentation} />
                             <Route
diff --git a/packages/website/ts/pages/not_found.tsx b/packages/website/ts/pages/not_found.tsx
index 2fe3b1f45..a7992a8fa 100644
--- a/packages/website/ts/pages/not_found.tsx
+++ b/packages/website/ts/pages/not_found.tsx
@@ -11,15 +11,15 @@ export interface NotFoundProps {
     dispatcher: Dispatcher;
 }
 
-export const NotFound = (_props: NotFoundProps) => {
+export const NotFound = (props: NotFoundProps) => {
     return (
         <div>
-            <TopBar blockchainIsLoaded={false} location={this.props.location} translate={this.props.translate} />
+            <TopBar blockchainIsLoaded={false} location={props.location} translate={props.translate} />
             <FullscreenMessage
                 headerText={'404 Not Found'}
                 bodyText={"Hm... looks like we couldn't find what you are looking for."}
             />
-            <Footer translate={this.props.translate} dispatcher={this.props.dispatcher} />
+            <Footer translate={props.translate} dispatcher={props.dispatcher} />
         </div>
     );
 };
diff --git a/packages/website/ts/types.ts b/packages/website/ts/types.ts
index 8a88c31b2..3211ddbd0 100644
--- a/packages/website/ts/types.ts
+++ b/packages/website/ts/types.ts
@@ -13,8 +13,8 @@ export interface Token {
     address: string;
     symbol: string;
     decimals: number;
-    isTracked: boolean;
     isRegistered: boolean;
+    trackedTimestamp?: number;
 }
 
 export interface TokenByAddress {
@@ -356,6 +356,7 @@ export enum WebsiteLegacyPaths {
 export enum WebsitePaths {
     Portal = '/portal',
     Wiki = '/wiki',
+    Docs = '/docs',
     ZeroExJs = '/docs/0x.js',
     Home = '/',
     FAQ = '/faq',
@@ -488,6 +489,16 @@ export enum Providers {
     Mist = 'MIST',
 }
 
+export interface InjectedProviderUpdate {
+    selectedAddress: string;
+    networkVersion: string;
+}
+
+export interface InjectedProviderObservable {
+    subscribe(updateHandler: (update: InjectedProviderUpdate) => void): void;
+    unsubscribe(updateHandler: (update: InjectedProviderUpdate) => void): void;
+}
+
 export interface TimestampMsRange {
     startTimestampMs: number;
     endTimestampMs: number;
diff --git a/packages/website/ts/utils/configs.ts b/packages/website/ts/utils/configs.ts
index ace8a5ba0..2f89f8ccb 100644
--- a/packages/website/ts/utils/configs.ts
+++ b/packages/website/ts/utils/configs.ts
@@ -63,10 +63,9 @@ export const configs = {
         TKN: '/images/token_icons/tokencard.png',
         TRST: '/images/token_icons/trust.png',
     } as { [symbol: string]: string },
-    IS_MAINNET_ENABLED: true,
     GOOGLE_ANALYTICS_ID: 'UA-98720122-1',
     LAST_LOCAL_STORAGE_FILL_CLEARANCE_DATE: '2017-11-22',
-    LAST_LOCAL_STORAGE_TRACKED_TOKEN_CLEARANCE_DATE: '2017-12-19',
+    LAST_LOCAL_STORAGE_TRACKED_TOKEN_CLEARANCE_DATE: '2018-6-25',
     OUTDATED_WRAPPED_ETHERS: [
         {
             42: {
diff --git a/packages/website/ts/utils/utils.ts b/packages/website/ts/utils/utils.ts
index ff06d923d..d12ae6a98 100644
--- a/packages/website/ts/utils/utils.ts
+++ b/packages/website/ts/utils/utils.ts
@@ -355,6 +355,11 @@ export const utils = {
         const token = _.find(tokens, { symbol });
         return token;
     },
+    getTrackedTokens(tokenByAddress: TokenByAddress): Token[] {
+        const allTokens = _.values(tokenByAddress);
+        const trackedTokens = _.filter(allTokens, t => this.isTokenTracked(t));
+        return trackedTokens;
+    },
     getFormattedAmountFromToken(token: Token, tokenState: TokenState): string {
         return utils.getFormattedAmount(tokenState.balance, token.decimals, token.symbol);
     },
@@ -381,4 +386,7 @@ export const utils = {
             return BrowserType.Other;
         }
     },
+    isTokenTracked(token: Token): boolean {
+        return !_.isUndefined(token.trackedTimestamp);
+    },
 };
diff --git a/yarn.lock b/yarn.lock
index 996dd28a9..e2c5ae483 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -44,6 +44,24 @@
     ethereumjs-util "5.1.5"
     lodash "4.17.10"
 
+"@0xproject/order-watcher@^0.0.6":
+  version "0.0.6"
+  resolved "https://registry.npmjs.org/@0xproject/order-watcher/-/order-watcher-0.0.6.tgz#85a8fb21e5755bb555f427b12d64d10b89b332e6"
+  dependencies:
+    "@0xproject/assert" "^0.2.12"
+    "@0xproject/base-contract" "^0.3.4"
+    "@0xproject/contract-wrappers" "^0.0.5"
+    "@0xproject/fill-scenarios" "^0.0.4"
+    "@0xproject/json-schemas" "^0.8.1"
+    "@0xproject/order-utils" "^0.0.7"
+    "@0xproject/types" "^0.8.1"
+    "@0xproject/typescript-typings" "^0.4.1"
+    "@0xproject/utils" "^0.7.1"
+    "@0xproject/web3-wrapper" "^0.7.1"
+    bintrees "1.0.2"
+    ethers "3.0.22"
+    lodash "4.17.10"
+
 "@0xproject/types@^0.5.0":
   version "0.5.0"
   resolved "https://registry.yarnpkg.com/@0xproject/types/-/types-0.5.0.tgz#ba3cfbc11a8c6344b57c9680aa7df2ea84b9bf05"
@@ -1708,7 +1726,7 @@ bindings@^1.2.1, bindings@^1.3.0:
   version "1.3.0"
   resolved "https://registry.yarnpkg.com/bindings/-/bindings-1.3.0.tgz#b346f6ecf6a95f5a815c5839fc7cdb22502f1ed7"
 
-bintrees@^1.0.2:
+bintrees@1.0.2, bintrees@^1.0.2:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/bintrees/-/bintrees-1.0.2.tgz#49f896d6e858a4a499df85c38fb399b9aff840f8"