130 files changed, 874 insertions, 936 deletions

diff --git a/packages/contracts/compiler.json b/packages/contracts/compiler.json
index 1ee58081a..56c8b1761 100644
--- a/packages/contracts/compiler.json
+++ b/packages/contracts/compiler.json
@@ -29,6 +29,7 @@
         "Exchange",
         "ExchangeWrapper",
         "IAssetData",
+        "IAssetProxy",
         "IValidator",
         "IWallet",
         "MixinAuthorizable",
diff --git a/packages/contracts/package.json b/packages/contracts/package.json
index b5a599fe5..e0e82adc7 100644
--- a/packages/contracts/package.json
+++ b/packages/contracts/package.json
@@ -14,7 +14,7 @@
         "watch_without_deps": "yarn pre_build && tsc -w",
         "build": "yarn pre_build && tsc",
         "pre_build": "run-s compile copy_artifacts generate_contract_wrappers",
-        "copy_artifacts": "copyfiles -u 4 '../migrations/artifacts/2.0.0/**/*' ./lib/src/artifacts;",
+        "copy_artifacts": "copyfiles -u 4 '../migrations/artifacts/2.0.0/**/*' ./lib/artifacts;",
         "test": "yarn run_mocha",
         "rebuild_and_test": "run-s build test",
         "test:coverage": "SOLIDITY_COVERAGE=true run-s build run_mocha coverage:report:text coverage:report:lcov",
@@ -22,10 +22,10 @@
         "test:trace": "SOLIDITY_REVERT_TRACE=true run-s build run_mocha",
         "run_mocha":
             "mocha --require source-map-support/register --require make-promises-safe 'lib/test/**/*.js' --timeout 100000 --bail --exit",
-        "compile": "sol-compiler",
-        "clean": "shx rm -rf lib src/generated_contract_wrappers",
+        "compile": "sol-compiler --contracts-dir src",
+        "clean": "shx rm -rf lib generated_contract_wrappers",
         "generate_contract_wrappers":
-            "abi-gen --abis  ${npm_package_config_abis} --template ../contract_templates/contract.handlebars --partials '../contract_templates/partials/**/*.handlebars' --output src/generated_contract_wrappers --backend ethers",
+            "abi-gen --abis  ${npm_package_config_abis} --template ../contract_templates/contract.handlebars --partials '../contract_templates/partials/**/*.handlebars' --output generated_contract_wrappers --backend ethers",
         "lint": "tslint --project . --exclude **/src/generated_contract_wrappers/**/* --exclude **/lib/**/*",
         "coverage:report:text": "istanbul report text",
         "coverage:report:html": "istanbul report html && open coverage/index.html",
@@ -35,7 +35,7 @@
     },
     "config": {
         "abis":
-            "../migrations/artifacts/2.0.0/@(AssetProxyOwner|DummyERC20Token|DummyERC721Receiver|DummyERC721Token|ERC20Proxy|ERC721Proxy|Exchange|ExchangeWrapper|IAssetData|MixinAuthorizable|MultiSigWallet|MultiSigWalletWithTimeLock|TestAssetProxyOwner|TestAssetProxyDispatcher|TestLibBytes|TestLibs|TestSignatureValidator|TestValidator|TestWallet|TokenRegistry|Whitelist|WETH9|ZRXToken).json"
+            "../migrations/artifacts/2.0.0/@(AssetProxyOwner|DummyERC20Token|DummyERC721Receiver|DummyERC721Token|ERC20Proxy|ERC721Proxy|Exchange|ExchangeWrapper|IAssetData|IAssetProxy|MixinAuthorizable|MultiSigWallet|MultiSigWalletWithTimeLock|TestAssetProxyOwner|TestAssetProxyDispatcher|TestLibBytes|TestLibs|TestSignatureValidator|TestValidator|TestWallet|TokenRegistry|Whitelist|WETH9|ZRXToken).json"
     },
     "repository": {
         "type": "git",
diff --git a/packages/contracts/src/contracts/previous/Arbitrage/Arbitrage.sol b/packages/contracts/src/1.0.0/Arbitrage/Arbitrage.sol
index 5054afc2f..5054afc2f 100644
--- a/packages/contracts/src/contracts/previous/Arbitrage/Arbitrage.sol
+++ b/packages/contracts/src/1.0.0/Arbitrage/Arbitrage.sol
diff --git a/packages/contracts/src/contracts/previous/ERC20Token/ERC20Token_v1.sol b/packages/contracts/src/1.0.0/ERC20Token/ERC20Token_v1.sol
index e05ee2d5e..e05ee2d5e 100644
--- a/packages/contracts/src/contracts/previous/ERC20Token/ERC20Token_v1.sol
+++ b/packages/contracts/src/1.0.0/ERC20Token/ERC20Token_v1.sol
diff --git a/packages/contracts/src/contracts/previous/EtherDelta/AccountLevels.sol b/packages/contracts/src/1.0.0/EtherDelta/AccountLevels.sol
index 8d7a930d3..8d7a930d3 100644
--- a/packages/contracts/src/contracts/previous/EtherDelta/AccountLevels.sol
+++ b/packages/contracts/src/1.0.0/EtherDelta/AccountLevels.sol
diff --git a/packages/contracts/src/contracts/previous/EtherDelta/EtherDelta.sol b/packages/contracts/src/1.0.0/EtherDelta/EtherDelta.sol
index fe599ca0a..fe599ca0a 100644
--- a/packages/contracts/src/contracts/previous/EtherDelta/EtherDelta.sol
+++ b/packages/contracts/src/1.0.0/EtherDelta/EtherDelta.sol
diff --git a/packages/contracts/src/contracts/previous/Exchange/Exchange_v1.sol b/packages/contracts/src/1.0.0/Exchange/Exchange_v1.sol
index 3f8e7368d..3f8e7368d 100644
--- a/packages/contracts/src/contracts/previous/Exchange/Exchange_v1.sol
+++ b/packages/contracts/src/1.0.0/Exchange/Exchange_v1.sol
diff --git a/packages/contracts/src/contracts/previous/Exchange/IExchange_v1.sol b/packages/contracts/src/1.0.0/Exchange/IExchange_v1.sol
index ec4bce7b0..ec4bce7b0 100644
--- a/packages/contracts/src/contracts/previous/Exchange/IExchange_v1.sol
+++ b/packages/contracts/src/1.0.0/Exchange/IExchange_v1.sol
diff --git a/packages/contracts/src/contracts/previous/MultiSigWalletWithTImeLockExceptRemoveAuthorizedAddress/MultiSigWalletWithTimeLockExceptRemoveAuthorizedAddress.sol b/packages/contracts/src/1.0.0/MultiSigWalletWithTImeLockExceptRemoveAuthorizedAddress/MultiSigWalletWithTimeLockExceptRemoveAuthorizedAddress.sol
index 241e02d4a..241e02d4a 100644
--- a/packages/contracts/src/contracts/previous/MultiSigWalletWithTImeLockExceptRemoveAuthorizedAddress/MultiSigWalletWithTimeLockExceptRemoveAuthorizedAddress.sol
+++ b/packages/contracts/src/1.0.0/MultiSigWalletWithTImeLockExceptRemoveAuthorizedAddress/MultiSigWalletWithTimeLockExceptRemoveAuthorizedAddress.sol
diff --git a/packages/contracts/src/contracts/previous/Ownable/IOwnable_v1.sol b/packages/contracts/src/1.0.0/Ownable/IOwnable_v1.sol
index 7e22d544d..7e22d544d 100644
--- a/packages/contracts/src/contracts/previous/Ownable/IOwnable_v1.sol
+++ b/packages/contracts/src/1.0.0/Ownable/IOwnable_v1.sol
diff --git a/packages/contracts/src/contracts/previous/Ownable/Ownable_v1.sol b/packages/contracts/src/1.0.0/Ownable/Ownable_v1.sol
index c87438fa4..c87438fa4 100644
--- a/packages/contracts/src/contracts/previous/Ownable/Ownable_v1.sol
+++ b/packages/contracts/src/1.0.0/Ownable/Ownable_v1.sol
diff --git a/packages/contracts/src/contracts/previous/SafeMath/SafeMath_v1.sol b/packages/contracts/src/1.0.0/SafeMath/SafeMath_v1.sol
index 341d611ec..341d611ec 100644
--- a/packages/contracts/src/contracts/previous/SafeMath/SafeMath_v1.sol
+++ b/packages/contracts/src/1.0.0/SafeMath/SafeMath_v1.sol
diff --git a/packages/contracts/src/contracts/previous/Token/Token_v1.sol b/packages/contracts/src/1.0.0/Token/Token_v1.sol
index de619fb7e..de619fb7e 100644
--- a/packages/contracts/src/contracts/previous/Token/Token_v1.sol
+++ b/packages/contracts/src/1.0.0/Token/Token_v1.sol
diff --git a/packages/contracts/src/contracts/previous/TokenRegistry/ITokenRegistery.sol b/packages/contracts/src/1.0.0/TokenRegistry/ITokenRegistery.sol
index b8bdaf3b9..b8bdaf3b9 100644
--- a/packages/contracts/src/contracts/previous/TokenRegistry/ITokenRegistery.sol
+++ b/packages/contracts/src/1.0.0/TokenRegistry/ITokenRegistery.sol
diff --git a/packages/contracts/src/contracts/previous/TokenRegistry/TokenRegistry.sol b/packages/contracts/src/1.0.0/TokenRegistry/TokenRegistry.sol
index 7417a10a3..7417a10a3 100644
--- a/packages/contracts/src/contracts/previous/TokenRegistry/TokenRegistry.sol
+++ b/packages/contracts/src/1.0.0/TokenRegistry/TokenRegistry.sol
diff --git a/packages/contracts/src/contracts/previous/TokenTransferProxy/TokenTransferProxy_v1.sol b/packages/contracts/src/1.0.0/TokenTransferProxy/TokenTransferProxy_v1.sol
index e3659d8ba..e3659d8ba 100644
--- a/packages/contracts/src/contracts/previous/TokenTransferProxy/TokenTransferProxy_v1.sol
+++ b/packages/contracts/src/1.0.0/TokenTransferProxy/TokenTransferProxy_v1.sol
diff --git a/packages/contracts/src/contracts/previous/UnlimitedAllowanceToken/UnlimitedAllowanceToken_v1.sol b/packages/contracts/src/1.0.0/UnlimitedAllowanceToken/UnlimitedAllowanceToken_v1.sol
index 46379c43d..46379c43d 100644
--- a/packages/contracts/src/contracts/previous/UnlimitedAllowanceToken/UnlimitedAllowanceToken_v1.sol
+++ b/packages/contracts/src/1.0.0/UnlimitedAllowanceToken/UnlimitedAllowanceToken_v1.sol
diff --git a/packages/contracts/src/contracts/current/multisig/MultiSigWallet.sol b/packages/contracts/src/2.0.0/multisig/MultiSigWallet.sol
index 79fd92029..79fd92029 100644
--- a/packages/contracts/src/contracts/current/multisig/MultiSigWallet.sol
+++ b/packages/contracts/src/2.0.0/multisig/MultiSigWallet.sol
diff --git a/packages/contracts/src/contracts/current/multisig/MultiSigWalletWithTimeLock.sol b/packages/contracts/src/2.0.0/multisig/MultiSigWalletWithTimeLock.sol
index 9766c2158..9766c2158 100644
--- a/packages/contracts/src/contracts/current/multisig/MultiSigWalletWithTimeLock.sol
+++ b/packages/contracts/src/2.0.0/multisig/MultiSigWalletWithTimeLock.sol
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC20Proxy.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC20Proxy.sol
new file mode 100644
index 000000000..aed62f54f
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC20Proxy.sol
@@ -0,0 +1,132 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../utils/LibBytes/LibBytes.sol";
+import "./MixinAuthorizable.sol";
+
+contract ERC20Proxy is
+    MixinAuthorizable
+{
+    // Id of this proxy.
+    bytes4 constant PROXY_ID = bytes4(keccak256("ERC20Token(address)"));
+    
+    function () 
+        external
+    {
+        assembly {
+            // The first 4 bytes of calldata holds the function selector
+            let selector := and(calldataload(0), 0xffffffff00000000000000000000000000000000000000000000000000000000)
+
+            // `transferFrom` will be called with the following parameters:
+            // assetData Encoded byte array.
+            // from Address to transfer asset from.
+            // to Address to transfer asset to.
+            // amount Amount of asset to transfer.
+            // bytes4(keccak256("transferFrom(bytes,address,address,uint256)")) = 0xa85e59e4
+            if eq(selector, 0xa85e59e400000000000000000000000000000000000000000000000000000000) {
+
+                // To lookup a value in a mapping, we load from the storage location keccak256(k, p),
+                // where k is the key left padded to 32 bytes and p is the storage slot
+                let start := mload(64)
+                mstore(start, and(caller, 0xffffffffffffffffffffffffffffffffffffffff))
+                mstore(add(start, 32), authorized_slot)
+
+                // Revert if authorized[msg.sender] == false
+                if iszero(sload(keccak256(start, 64))) {
+                    // Revert with `Error("SENDER_NOT_AUTHORIZED")`
+                    mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+                    mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+                    mstore(64, 0x0000001553454e4445525f4e4f545f415554484f52495a454400000000000000)
+                    mstore(96, 0)
+                    revert(0, 100)
+                }
+                
+                /////// Token contract address ///////
+                // The token address is found as follows:
+                // * It is stored at offset 4 in `assetData` contents.
+                // * This is stored at offset 32 from `assetData`.
+                // * The offset to `assetData` from Params is stored at offset
+                //   4 in calldata.
+                // * The offset of Params in calldata is 4.
+                // So we read location 4 and add 32 + 4 + 4 to it.
+                let token := calldataload(add(calldataload(4), 40))
+                
+                /////// Setup Header Area ///////
+                // This area holds the 4-byte `transferFrom` selector.
+                // Any trailing data in transferFromSelector will be
+                // overwritten in the next `mstore` call.
+                mstore(0, 0x23b872dd00000000000000000000000000000000000000000000000000000000)
+                
+                /////// Setup Params Area ///////
+                // We copy the fields `from`, `to` and `amount` in bulk
+                // from our own calldata to the new calldata.
+                calldatacopy(4, 36, 96)
+
+                /////// Call `token.transferFrom` using the calldata ///////
+                let success := call(
+                    gas,            // forward all gas
+                    token,          // call address of token contract
+                    0,              // don't send any ETH
+                    0,              // pointer to start of input
+                    100,            // length of input
+                    0,              // write output over input
+                    32              // output size should be 32 bytes
+                )
+
+                /////// Check return data. ///////
+                // If there is no return data, we assume the token incorrectly
+                // does not return a bool. In this case we expect it to revert
+                // on failure, which was handled above.
+                // If the token does return data, we require that it is a single
+                // nonzero 32 bytes value.
+                // So the transfer succeeded if the call succeeded and either
+                // returned nothing, or returned a non-zero 32 byte value. 
+                success := and(success, or(
+                    iszero(returndatasize),
+                    and(
+                        eq(returndatasize, 32),
+                        gt(mload(0), 0)
+                    )
+                ))
+                if success {
+                    return(0, 0)
+                }
+                
+                // Revert with `Error("TRANSFER_FAILED")`
+                mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+                mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+                mstore(64, 0x0000000f5452414e534645525f4641494c454400000000000000000000000000)
+                mstore(96, 0)
+                revert(0, 100)
+            }
+        }
+    }
+
+    /// @dev Gets the proxy id associated with the proxy address.
+    /// @return Proxy id.
+    function getProxyId()
+        external
+        pure
+        returns (bytes4)
+    {
+        return PROXY_ID;
+    }
+}
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol
new file mode 100644
index 000000000..b73dc36cc
--- /dev/null
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol
@@ -0,0 +1,218 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity ^0.4.24;
+pragma experimental ABIEncoderV2;
+
+import "../../utils/LibBytes/LibBytes.sol";
+import "./MixinAuthorizable.sol";
+
+contract ERC721Proxy is
+    MixinAuthorizable
+{
+    // Id of this proxy.
+    bytes4 constant PROXY_ID = bytes4(keccak256("ERC721Token(address,uint256,bytes)"));
+
+    function () 
+        external
+    {
+        assembly {
+            // The first 4 bytes of calldata holds the function selector
+            let selector := and(calldataload(0), 0xffffffff00000000000000000000000000000000000000000000000000000000)
+
+            // `transferFrom` will be called with the following parameters:
+            // assetData Encoded byte array.
+            // from Address to transfer asset from.
+            // to Address to transfer asset to.
+            // amount Amount of asset to transfer.
+            // bytes4(keccak256("transferFrom(bytes,address,address,uint256)")) = 0xa85e59e4
+            if eq(selector, 0xa85e59e400000000000000000000000000000000000000000000000000000000) {
+
+                // To lookup a value in a mapping, we load from the storage location keccak256(k, p),
+                // where k is the key left padded to 32 bytes and p is the storage slot
+                let start := mload(64)
+                mstore(start, and(caller, 0xffffffffffffffffffffffffffffffffffffffff))
+                mstore(add(start, 32), authorized_slot)
+
+                // Revert if authorized[msg.sender] == false
+                if iszero(sload(keccak256(start, 64))) {
+                    // Revert with `Error("SENDER_NOT_AUTHORIZED")`
+                    mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+                    mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+                    mstore(64, 0x0000001553454e4445525f4e4f545f415554484f52495a454400000000000000)
+                    mstore(96, 0)
+                    revert(0, 100)
+                }
+
+                // `transferFrom`.
+                // The function is marked `external`, so no abi decodeding is done for
+                // us. Instead, we expect the `calldata` memory to contain the
+                // following:
+                //
+                // | Area     | Offset | Length  | Contents                            |
+                // |----------|--------|---------|-------------------------------------|
+                // | Header   | 0      | 4       | function selector                   |
+                // | Params   |        | 4 * 32  | function parameters:                |
+                // |          | 4      |         |   1. offset to assetData (*)        |
+                // |          | 36     |         |   2. from                           |
+                // |          | 68     |         |   3. to                             |
+                // |          | 100    |         |   4. amount                         |
+                // | Data     |        |         | assetData:                          |
+                // |          | 132    | 32      | assetData Length                    |
+                // |          | 164    | **      | assetData Contents                  |
+                //
+                // (*): offset is computed from start of function parameters, so offset
+                //      by an additional 4 bytes in the calldata.
+                //
+                // WARNING: The ABIv2 specification allows additional padding between
+                //          the Params and Data section. This will result in a larger
+                //          offset to assetData.
+                
+                // Asset data itself is encoded as follows:
+                //
+                // | Area     | Offset | Length  | Contents                            |
+                // |----------|--------|---------|-------------------------------------|
+                // | Header   | 0      | 4       | function selector                   |
+                // | Params   |        | 3 * 32  | function parameters:                |
+                // |          | 4      | 12 + 20 |   1. token address                  |
+                // |          | 36     |         |   2. tokenId                        |
+                // |          | 68     |         |   3. offset to receiverData (*)     |
+                // | Data     |        |         | receiverData:                       |
+                // |          | 100    | 32      | receiverData Length                 |
+                // |          | 132    | **      | receiverData Contents               |
+                
+                // We construct calldata for the `token.safeTransferFrom` ABI.
+                // The layout of this calldata is in the table below.
+                // 
+                // | Area     | Offset | Length  | Contents                            |
+                // |----------|--------|---------|-------------------------------------|
+                // | Header   | 0      | 4       | function selector                   |
+                // | Params   |        | 4 * 32  | function parameters:                |
+                // |          | 4      |         |   1. from                           |
+                // |          | 36     |         |   2. to                             |
+                // |          | 68     |         |   3. tokenId                        |
+                // |          | 100    |         |   4. offset to receiverData (*)     |
+                // | Data     |        |         | receiverData:                       |
+                // |          | 132    | 32      | receiverData Length                 |
+                // |          | 164    | **      | receiverData Contents               |
+
+                // There exists only 1 of each token.
+                // require(amount == 1, "INVALID_AMOUNT")
+                if sub(calldataload(100), 1) {
+                    // Revert with `Error("INVALID_AMOUNT")`
+                    mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+                    mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+                    mstore(64, 0x0000000e494e56414c49445f414d4f554e540000000000000000000000000000)
+                    mstore(96, 0)
+                    revert(0, 100)
+                }
+                
+                // Require assetData to be at least 132 bytes
+                let offset := calldataload(4)
+                if lt(calldataload(add(offset, 4)), 132) {
+                    // Revert with `Error("LENGTH_GREATER_THAN_131_REQUIRED")`
+                    mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+                    mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+                    mstore(64, 0x000000204c454e4754485f475245415445525f5448414e5f3133315f52455155)
+                    mstore(96, 0x4952454400000000000000000000000000000000000000000000000000000000)
+                    revert(0, 100)
+                }
+                
+                /////// Setup State ///////
+                // `cdStart` is the start of the calldata for
+                // `token.safeTransferFrom` (equal to free memory ptr).
+                let cdStart := mload(64)
+                // `dataAreaLength` is the total number of words
+                // needed to store `receiverData`
+                // As-per the ABI spec, this value is padded up to
+                // the nearest multiple of 32,
+                // and includes 32-bytes for length.
+                // It's calculated as folows:
+                //      - Unpadded length in bytes = `mload(receiverData) + 32`
+                //      - Add 31 to convert rounding down to rounding up.
+                //        Combined with the previous and this is `63`.
+                //      - Round down to nearest multiple of 32 by clearing
+                //        bits 0x1F. This is done with `and` and a mask.
+
+                /////// Setup Header Area ///////
+                // This area holds the 4-byte `transferFromSelector`.
+                // Any trailing data in transferFromSelector will be
+                // overwritten in the next `mstore` call.
+                mstore(cdStart, 0xb88d4fde00000000000000000000000000000000000000000000000000000000)
+                
+                /////// Setup Params Area ///////
+                // Each parameter is padded to 32-bytes.
+                // The entire Params Area is 128 bytes.
+                // Notes:
+                //   1. A 20-byte mask is applied to addresses
+                //      to zero-out the unused bytes.
+                //   2. The offset to `receiverData` is the length
+                //      of the Params Area (128 bytes).
+                
+                let length := calldataload(add(offset, 136))
+                let token := calldataload(add(offset, 40))
+                
+                // Round length up to multiple of 32
+                length := and(add(length, 31), 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFE0)
+                
+                // Copy `from` and `to`
+                calldatacopy(add(cdStart, 4), 36, 64)
+                
+                // TokenId
+                mstore(add(cdStart, 68), calldataload(add(offset, 72)))
+                
+                // Offset to receiverData
+                mstore(add(cdStart, 100), 128)
+                
+                // receiverData (including length)
+                calldatacopy(add(cdStart, 132), add(offset, 136), add(length, 32))
+                
+                /////// Call `token.safeTransferFrom` using the calldata ///////
+                let success := call(
+                    gas,                    // forward all gas
+                    token,                  // call address of token contract
+                    0,                      // don't send any ETH
+                    cdStart,                // pointer to start of input
+                    add(length, 164),       // length of input
+                    0,                      // write output to null
+                    0                       // output size is 0 bytes
+                )
+                if success {
+                    return(0, 0)
+                }
+                
+                // Revert with `Error("TRANSFER_FAILED")`
+                mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
+                mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
+                mstore(64, 0x0000000f5452414e534645525f4641494c454400000000000000000000000000)
+                mstore(96, 0)
+                revert(0, 100)
+            }
+        }
+    }
+
+    /// @dev Gets the proxy id associated with the proxy address.
+    /// @return Proxy id.
+    function getProxyId()
+        external
+        pure
+        returns (bytes4)
+    {
+        return PROXY_ID;
+    }
+}
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAuthorizable.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/MixinAuthorizable.sol
index 3b9584a44..3b9584a44 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/MixinAuthorizable.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/MixinAuthorizable.sol
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/interfaces/IAssetData.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetData.sol
index 8c78ee8c4..7ebd6acf0 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/interfaces/IAssetData.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetData.sol
@@ -23,14 +23,16 @@ pragma solidity ^0.4.23;
 // This argument is ABI encoded as one of the methods of this interface.
 interface IAssetData {
     
-    function ERC20Token(
-        address tokenContract)
-        external pure;
+    function ERC20Token(address tokenContract)
+        external
+        pure;
     
     function ERC721Token(
         address tokenContract,
         uint256 tokenId,
-        bytes receiverData)
-        external pure;
+        bytes receiverData
+    )
+        external
+        pure;
     
 }
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/interfaces/IAssetProxy.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetProxy.sol
index ae8e195da..eacd5a412 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/interfaces/IAssetProxy.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetProxy.sol
@@ -42,6 +42,6 @@ contract IAssetProxy is
     /// @return Proxy id.
     function getProxyId()
         external
-        view
+        pure
         returns (bytes4);
 }
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/interfaces/IAuthorizable.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAuthorizable.sol
index cedd1744c..cedd1744c 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/interfaces/IAuthorizable.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAuthorizable.sol
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibAssetProxyErrors.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/libs/LibAssetProxyErrors.sol
index 338cb12e2..338cb12e2 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/libs/LibAssetProxyErrors.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/libs/LibAssetProxyErrors.sol
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/mixins/MAuthorizable.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/mixins/MAuthorizable.sol
index 6f35bd7ec..6f35bd7ec 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/mixins/MAuthorizable.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/mixins/MAuthorizable.sol
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxyOwner/AssetProxyOwner.sol b/packages/contracts/src/2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol
index eb58b3374..eb58b3374 100644
--- a/packages/contracts/src/contracts/current/protocol/AssetProxyOwner/AssetProxyOwner.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/Exchange.sol b/packages/contracts/src/2.0.0/protocol/Exchange/Exchange.sol
index d36e9633e..d36e9633e 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/Exchange.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/Exchange.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinAssetProxyDispatcher.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol
index f7086f543..9e9d88ce7 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinAssetProxyDispatcher.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol
@@ -32,43 +32,28 @@ contract MixinAssetProxyDispatcher is
     // Mapping from Asset Proxy Id's to their respective Asset Proxy
     mapping (bytes4 => IAssetProxy) public assetProxies;
 
-    /// @dev Registers an asset proxy to an asset proxy id.
-    ///      An id can only be assigned to a single proxy at a given time.
-    /// @param assetProxyId Id to register`newAssetProxy` under.
-    /// @param newAssetProxy Address of new asset proxy to register, or 0x0 to unset assetProxyId.
-    /// @param oldAssetProxy Existing asset proxy to overwrite, or 0x0 if assetProxyId is currently unused.
-    function registerAssetProxy(
-        bytes4 assetProxyId,
-        address newAssetProxy,
-        address oldAssetProxy
-    )
+    /// @dev Registers an asset proxy to its asset proxy id.
+    ///      Once an asset proxy is registered, it cannot be unregistered.
+    /// @param assetProxy Address of new asset proxy to register.
+    function registerAssetProxy(address assetProxy)
         external
         onlyOwner
     {
-        // Ensure the existing asset proxy is not unintentionally overwritten
+        IAssetProxy assetProxyContract = IAssetProxy(assetProxy);
+
+        // Ensure that no asset proxy exists with current id.
+        bytes4 assetProxyId = assetProxyContract.getProxyId();
         address currentAssetProxy = assetProxies[assetProxyId];
         require(
-            oldAssetProxy == currentAssetProxy,
-            "ASSET_PROXY_MISMATCH"
+            currentAssetProxy == address(0),
+            "ASSET_PROXY_ALREADY_EXISTS"
         );
 
-        IAssetProxy assetProxy = IAssetProxy(newAssetProxy);
-
-        // Ensure that the id of newAssetProxy matches the passed in assetProxyId, unless it is being reset to 0.
-        if (newAssetProxy != address(0)) {
-            bytes4 newAssetProxyId = assetProxy.getProxyId();
-            require(
-                newAssetProxyId == assetProxyId,
-                "ASSET_PROXY_ID_MISMATCH"
-            );
-        }
-
         // Add asset proxy and log registration.
-        assetProxies[assetProxyId] = assetProxy;
-        emit AssetProxySet(
+        assetProxies[assetProxyId] = assetProxyContract;
+        emit AssetProxyRegistered(
             assetProxyId,
-            newAssetProxy,
-            oldAssetProxy
+            assetProxy
         );
     }
 
@@ -112,7 +97,7 @@ contract MixinAssetProxyDispatcher is
                     0xFFFFFFFF00000000000000000000000000000000000000000000000000000000
                 )
             }
-            IAssetProxy assetProxy = assetProxies[assetProxyId];
+            address assetProxy = assetProxies[assetProxyId];
 
             // Ensure that assetProxy exists
             require(
@@ -135,7 +120,6 @@ contract MixinAssetProxyDispatcher is
             // |          | 132    | 32      | assetData Length                            |
             // |          | 164    | **      | assetData Contents                          |
 
-            bool success;
             assembly {
                 /////// Setup State ///////
                 // `cdStart` is the start of the calldata for `assetProxy.transferFrom` (equal to free memory ptr).
@@ -173,7 +157,7 @@ contract MixinAssetProxyDispatcher is
                 }
 
                 /////// Call `assetProxy.transferFrom` using the constructed calldata ///////
-                success := call(
+                let success := call(
                     gas,                    // forward all gas
                     assetProxy,             // call address of asset proxy
                     0,                      // don't send any ETH
@@ -182,7 +166,7 @@ contract MixinAssetProxyDispatcher is
                     cdStart,                // write output over input
                     512                     // reserve 512 bytes for output
                 )
-                if eq(success, 0) {
+                if iszero(success) {
                     revert(cdStart, returndatasize())
                 }
             }
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinExchangeCore.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol
index c0ed023ac..c0ed023ac 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinExchangeCore.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinMatchOrders.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinMatchOrders.sol
index 1a43eec79..1a43eec79 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinMatchOrders.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinMatchOrders.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinSignatureValidator.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol
index 29172057a..29172057a 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinSignatureValidator.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinTransactions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol
index e0f450d0a..31f7f2847 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinTransactions.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol
@@ -60,6 +60,13 @@ contract MixinTransactions is
     {
         bytes32 schemaHash = EIP712_ZEROEX_TRANSACTION_SCHEMA_HASH;
         bytes32 dataHash = keccak256(data);
+        // Assembly for more efficiently computing:
+        // keccak256(abi.encode(
+        //   EIP712_ZEROEX_TRANSACTION_SCHEMA_HASH,
+        //   salt,
+        //   signerAddress,
+        //   keccak256(data)
+        //  ));
         assembly {
             let memPtr := mload(64)
             mstore(memPtr, schemaHash)
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/MixinWrapperFunctions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinWrapperFunctions.sol
index 00668ca43..00668ca43 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/MixinWrapperFunctions.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinWrapperFunctions.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IAssetProxyDispatcher.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IAssetProxyDispatcher.sol
index fa55dff00..66f3b5796 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IAssetProxyDispatcher.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IAssetProxyDispatcher.sol
@@ -20,16 +20,10 @@ pragma solidity ^0.4.24;
 
 contract IAssetProxyDispatcher {
 
-    /// @dev Registers an asset proxy to an asset proxy id.
-    ///      An id can only be assigned to a single proxy at a given time.
-    /// @param assetProxyId Id to register`newAssetProxy` under.
-    /// @param newAssetProxy Address of new asset proxy to register, or 0x0 to unset assetProxyId.
-    /// @param oldAssetProxy Existing asset proxy to overwrite, or 0x0 if assetProxyId is currently unused.
-    function registerAssetProxy(
-        bytes4 assetProxyId,
-        address newAssetProxy,
-        address oldAssetProxy
-    )
+    /// @dev Registers an asset proxy to its asset proxy id.
+    ///      Once an asset proxy is registered, it cannot be unregistered.
+    /// @param assetProxy Address of new asset proxy to register.
+    function registerAssetProxy(address assetProxy)
         external;
 
     /// @dev Gets an asset proxy.
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IExchange.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IExchange.sol
index 9f21c18d7..9f21c18d7 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IExchange.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IExchange.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IExchangeCore.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IExchangeCore.sol
index 98222f33f..98222f33f 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IExchangeCore.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IExchangeCore.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IMatchOrders.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IMatchOrders.sol
index df009d063..df009d063 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IMatchOrders.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IMatchOrders.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/ISignatureValidator.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/ISignatureValidator.sol
index 511463309..511463309 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/ISignatureValidator.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/ISignatureValidator.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/ITransactions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/ITransactions.sol
index a7cab8f55..a7cab8f55 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/ITransactions.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/ITransactions.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IValidator.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IValidator.sol
index 0b1796a66..0b1796a66 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IValidator.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IValidator.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IWallet.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IWallet.sol
index c86a2c057..c86a2c057 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IWallet.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IWallet.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IWrapperFunctions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IWrapperFunctions.sol
index 84bb683bc..84bb683bc 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/interfaces/IWrapperFunctions.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/interfaces/IWrapperFunctions.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibConstants.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibConstants.sol
index 488ca956c..488ca956c 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibConstants.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibConstants.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibEIP712.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol
index b983347a4..b983347a4 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibEIP712.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibExchangeErrors.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibExchangeErrors.sol
index e37f41ada..01aa78a1d 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibExchangeErrors.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibExchangeErrors.sol
@@ -54,8 +54,7 @@ contract LibExchangeErrors {
     string constant FAILED_EXECUTION = "FAILED_EXECUTION";                              // Transaction execution failed. 
     
     /// registerAssetProxy errors ///
-    string constant ASSET_PROXY_MISMATCH = "ASSET_PROXY_MISMATCH";                      // oldAssetProxy proxy does not match currentAssetProxy. 
-    string constant ASSET_PROXY_ID_MISMATCH = "ASSET_PROXY_ID_MISMATCH";                // newAssetProxyId does not match given assetProxyId.
+    string constant ASSET_PROXY_ALREADY_EXISTS = "ASSET_PROXY_ALREADY_EXISTS";          // AssetProxy with same id already exists.
 
     /// dispatchTransferFrom errors ///
     string constant ASSET_PROXY_DOES_NOT_EXIST = "ASSET_PROXY_DOES_NOT_EXIST";          // No assetProxy registered at given id.
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibFillResults.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibFillResults.sol
index 63f1b8c87..63f1b8c87 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibFillResults.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibFillResults.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibMath.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibMath.sol
index bfe2fd33f..bfe2fd33f 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibMath.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibMath.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibOrder.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol
index f3f1e9277..954f94f76 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/libs/LibOrder.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol
@@ -98,6 +98,21 @@ contract LibOrder is
         bytes32 schemaHash = EIP712_ORDER_SCHEMA_HASH;
         bytes32 makerAssetDataHash = keccak256(order.makerAssetData);
         bytes32 takerAssetDataHash = keccak256(order.takerAssetData);
+        // Assembly for more efficiently computing:
+        //   keccak256(abi.encode(
+        //       order.makerAddress,
+        //       order.takerAddress,
+        //       order.feeRecipientAddress,
+        //       order.senderAddress,
+        //       order.makerAssetAmount,
+        //       order.takerAssetAmount,
+        //       order.makerFee,
+        //       order.takerFee,
+        //       order.expirationTimeSeconds,
+        //       order.salt,
+        //       keccak256(order.makerAssetData),
+        //       keccak256(order.takerAssetData)
+        //   ));
         assembly {
             // Backup
             let temp1 := mload(sub(order,  32))
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MAssetProxyDispatcher.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MAssetProxyDispatcher.sol
index c2b506dcf..5bf59c6ce 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MAssetProxyDispatcher.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MAssetProxyDispatcher.sol
@@ -26,10 +26,9 @@ contract MAssetProxyDispatcher is
 {
 
     // Logs registration of new asset proxy
-    event AssetProxySet(
+    event AssetProxyRegistered(
         bytes4 id,              // Id of new registered AssetProxy.
-        address newAssetProxy,  // Address of new registered AssetProxy.
-        address oldAssetProxy   // Address of AssetProxy that was overwritten at given id (or null address).
+        address assetProxy      // Address of new registered AssetProxy.
     );
 
     /// @dev Forwards arguments to assetProxy and calls `transferFrom`. Either succeeds or throws.
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MExchangeCore.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MExchangeCore.sol
index 6e406e1c4..6e406e1c4 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MExchangeCore.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MExchangeCore.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MMatchOrders.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MMatchOrders.sol
index abe7c3596..abe7c3596 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MMatchOrders.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MMatchOrders.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MSignatureValidator.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MSignatureValidator.sol
index 6cc1d7a10..6cc1d7a10 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MSignatureValidator.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MSignatureValidator.sol
diff --git a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MTransactions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MTransactions.sol
index e2f89de01..e2f89de01 100644
--- a/packages/contracts/src/contracts/current/protocol/Exchange/mixins/MTransactions.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MTransactions.sol
diff --git a/packages/contracts/src/contracts/current/test/DummyERC20Token/DummyERC20Token.sol b/packages/contracts/src/2.0.0/test/DummyERC20Token/DummyERC20Token.sol
index b2fe2df06..b2fe2df06 100644
--- a/packages/contracts/src/contracts/current/test/DummyERC20Token/DummyERC20Token.sol
+++ b/packages/contracts/src/2.0.0/test/DummyERC20Token/DummyERC20Token.sol
diff --git a/packages/contracts/src/contracts/current/test/DummyERC721Receiver/DummyERC721Receiver.sol b/packages/contracts/src/2.0.0/test/DummyERC721Receiver/DummyERC721Receiver.sol
index c584d0b54..c584d0b54 100644
--- a/packages/contracts/src/contracts/current/test/DummyERC721Receiver/DummyERC721Receiver.sol
+++ b/packages/contracts/src/2.0.0/test/DummyERC721Receiver/DummyERC721Receiver.sol
diff --git a/packages/contracts/src/contracts/current/test/DummyERC721Token/DummyERC721Token.sol b/packages/contracts/src/2.0.0/test/DummyERC721Token/DummyERC721Token.sol
index 78ea96447..78ea96447 100644
--- a/packages/contracts/src/contracts/current/test/DummyERC721Token/DummyERC721Token.sol
+++ b/packages/contracts/src/2.0.0/test/DummyERC721Token/DummyERC721Token.sol
diff --git a/packages/contracts/src/contracts/current/test/ExchangeWrapper/ExchangeWrapper.sol b/packages/contracts/src/2.0.0/test/ExchangeWrapper/ExchangeWrapper.sol
index 5baaf6e5a..5baaf6e5a 100644
--- a/packages/contracts/src/contracts/current/test/ExchangeWrapper/ExchangeWrapper.sol
+++ b/packages/contracts/src/2.0.0/test/ExchangeWrapper/ExchangeWrapper.sol
diff --git a/packages/contracts/src/contracts/current/test/Mintable/Mintable.sol b/packages/contracts/src/2.0.0/test/Mintable/Mintable.sol
index a91bfee9e..a91bfee9e 100644
--- a/packages/contracts/src/contracts/current/test/Mintable/Mintable.sol
+++ b/packages/contracts/src/2.0.0/test/Mintable/Mintable.sol
diff --git a/packages/contracts/src/contracts/current/test/TestAssetProxyDispatcher/TestAssetProxyDispatcher.sol b/packages/contracts/src/2.0.0/test/TestAssetProxyDispatcher/TestAssetProxyDispatcher.sol
index 2ae69e0ef..2ae69e0ef 100644
--- a/packages/contracts/src/contracts/current/test/TestAssetProxyDispatcher/TestAssetProxyDispatcher.sol
+++ b/packages/contracts/src/2.0.0/test/TestAssetProxyDispatcher/TestAssetProxyDispatcher.sol
diff --git a/packages/contracts/src/contracts/current/test/TestAssetProxyOwner/TestAssetProxyOwner.sol b/packages/contracts/src/2.0.0/test/TestAssetProxyOwner/TestAssetProxyOwner.sol
index 2abcd17a0..2abcd17a0 100644
--- a/packages/contracts/src/contracts/current/test/TestAssetProxyOwner/TestAssetProxyOwner.sol
+++ b/packages/contracts/src/2.0.0/test/TestAssetProxyOwner/TestAssetProxyOwner.sol
diff --git a/packages/contracts/src/contracts/current/test/TestLibBytes/TestLibBytes.sol b/packages/contracts/src/2.0.0/test/TestLibBytes/TestLibBytes.sol
index f45faaf36..f45faaf36 100644
--- a/packages/contracts/src/contracts/current/test/TestLibBytes/TestLibBytes.sol
+++ b/packages/contracts/src/2.0.0/test/TestLibBytes/TestLibBytes.sol
diff --git a/packages/contracts/src/contracts/current/test/TestLibs/TestLibs.sol b/packages/contracts/src/2.0.0/test/TestLibs/TestLibs.sol
index 010080703..010080703 100644
--- a/packages/contracts/src/contracts/current/test/TestLibs/TestLibs.sol
+++ b/packages/contracts/src/2.0.0/test/TestLibs/TestLibs.sol
diff --git a/packages/contracts/src/contracts/current/test/TestSignatureValidator/TestSignatureValidator.sol b/packages/contracts/src/2.0.0/test/TestSignatureValidator/TestSignatureValidator.sol
index 0f84678cf..0f84678cf 100644
--- a/packages/contracts/src/contracts/current/test/TestSignatureValidator/TestSignatureValidator.sol
+++ b/packages/contracts/src/2.0.0/test/TestSignatureValidator/TestSignatureValidator.sol
diff --git a/packages/contracts/src/contracts/current/test/TestValidator/TestValidator.sol b/packages/contracts/src/2.0.0/test/TestValidator/TestValidator.sol
index f9271bf7a..f9271bf7a 100644
--- a/packages/contracts/src/contracts/current/test/TestValidator/TestValidator.sol
+++ b/packages/contracts/src/2.0.0/test/TestValidator/TestValidator.sol
diff --git a/packages/contracts/src/contracts/current/test/TestWallet/TestWallet.sol b/packages/contracts/src/2.0.0/test/TestWallet/TestWallet.sol
index 17dee9e9c..17dee9e9c 100644
--- a/packages/contracts/src/contracts/current/test/TestWallet/TestWallet.sol
+++ b/packages/contracts/src/2.0.0/test/TestWallet/TestWallet.sol
diff --git a/packages/contracts/src/contracts/current/test/Whitelist/Whitelist.sol b/packages/contracts/src/2.0.0/test/Whitelist/Whitelist.sol
index 8b52858b1..8b52858b1 100644
--- a/packages/contracts/src/contracts/current/test/Whitelist/Whitelist.sol
+++ b/packages/contracts/src/2.0.0/test/Whitelist/Whitelist.sol
diff --git a/packages/contracts/src/contracts/current/tokens/ERC20Token/ERC20Token.sol b/packages/contracts/src/2.0.0/tokens/ERC20Token/ERC20Token.sol
index b6961a6ec..b6961a6ec 100644
--- a/packages/contracts/src/contracts/current/tokens/ERC20Token/ERC20Token.sol
+++ b/packages/contracts/src/2.0.0/tokens/ERC20Token/ERC20Token.sol
diff --git a/packages/contracts/src/contracts/current/tokens/ERC20Token/IERC20Token.sol b/packages/contracts/src/2.0.0/tokens/ERC20Token/IERC20Token.sol
index eb879b6a8..eb879b6a8 100644
--- a/packages/contracts/src/contracts/current/tokens/ERC20Token/IERC20Token.sol
+++ b/packages/contracts/src/2.0.0/tokens/ERC20Token/IERC20Token.sol
diff --git a/packages/contracts/src/contracts/current/tokens/ERC721Token/ERC721Token.sol b/packages/contracts/src/2.0.0/tokens/ERC721Token/ERC721Token.sol
index 41ba149e3..41ba149e3 100644
--- a/packages/contracts/src/contracts/current/tokens/ERC721Token/ERC721Token.sol
+++ b/packages/contracts/src/2.0.0/tokens/ERC721Token/ERC721Token.sol
diff --git a/packages/contracts/src/contracts/current/tokens/ERC721Token/IERC721Receiver.sol b/packages/contracts/src/2.0.0/tokens/ERC721Token/IERC721Receiver.sol
index b0fff3c90..b0fff3c90 100644
--- a/packages/contracts/src/contracts/current/tokens/ERC721Token/IERC721Receiver.sol
+++ b/packages/contracts/src/2.0.0/tokens/ERC721Token/IERC721Receiver.sol
diff --git a/packages/contracts/src/contracts/current/tokens/ERC721Token/IERC721Token.sol b/packages/contracts/src/2.0.0/tokens/ERC721Token/IERC721Token.sol
index 345712d67..345712d67 100644
--- a/packages/contracts/src/contracts/current/tokens/ERC721Token/IERC721Token.sol
+++ b/packages/contracts/src/2.0.0/tokens/ERC721Token/IERC721Token.sol
diff --git a/packages/contracts/src/contracts/current/tokens/UnlimitedAllowanceToken/UnlimitedAllowanceToken.sol b/packages/contracts/src/2.0.0/tokens/UnlimitedAllowanceToken/UnlimitedAllowanceToken.sol
index f62602ab3..f62602ab3 100644
--- a/packages/contracts/src/contracts/current/tokens/UnlimitedAllowanceToken/UnlimitedAllowanceToken.sol
+++ b/packages/contracts/src/2.0.0/tokens/UnlimitedAllowanceToken/UnlimitedAllowanceToken.sol
diff --git a/packages/contracts/src/contracts/current/tokens/WETH9/WETH9.sol b/packages/contracts/src/2.0.0/tokens/WETH9/WETH9.sol
index 733ca414b..733ca414b 100644
--- a/packages/contracts/src/contracts/current/tokens/WETH9/WETH9.sol
+++ b/packages/contracts/src/2.0.0/tokens/WETH9/WETH9.sol
diff --git a/packages/contracts/src/contracts/current/tokens/ZRXToken/ZRXToken.sol b/packages/contracts/src/2.0.0/tokens/ZRXToken/ZRXToken.sol
index 2d8e74f2c..2e5b61e0b 100644
--- a/packages/contracts/src/contracts/current/tokens/ZRXToken/ZRXToken.sol
+++ b/packages/contracts/src/2.0.0/tokens/ZRXToken/ZRXToken.sol
@@ -18,7 +18,7 @@
 
 pragma solidity ^0.4.11;
 
-import { UnlimitedAllowanceToken_v1 as UnlimitedAllowanceToken } from "../../../previous/UnlimitedAllowanceToken/UnlimitedAllowanceToken_v1.sol";
+import { UnlimitedAllowanceToken_v1 as UnlimitedAllowanceToken } from "../../../1.0.0/UnlimitedAllowanceToken/UnlimitedAllowanceToken_v1.sol";
 
 contract ZRXToken is UnlimitedAllowanceToken {
 
diff --git a/packages/contracts/src/contracts/current/utils/LibBytes/LibBytes.sol b/packages/contracts/src/2.0.0/utils/LibBytes/LibBytes.sol
index 78b1ddf7c..78b1ddf7c 100644
--- a/packages/contracts/src/contracts/current/utils/LibBytes/LibBytes.sol
+++ b/packages/contracts/src/2.0.0/utils/LibBytes/LibBytes.sol
diff --git a/packages/contracts/src/contracts/current/utils/Ownable/IOwnable.sol b/packages/contracts/src/2.0.0/utils/Ownable/IOwnable.sol
index e77680903..e77680903 100644
--- a/packages/contracts/src/contracts/current/utils/Ownable/IOwnable.sol
+++ b/packages/contracts/src/2.0.0/utils/Ownable/IOwnable.sol
diff --git a/packages/contracts/src/contracts/current/utils/Ownable/Ownable.sol b/packages/contracts/src/2.0.0/utils/Ownable/Ownable.sol
index 6f5761cc7..6f5761cc7 100644
--- a/packages/contracts/src/contracts/current/utils/Ownable/Ownable.sol
+++ b/packages/contracts/src/2.0.0/utils/Ownable/Ownable.sol
diff --git a/packages/contracts/src/contracts/current/utils/SafeMath/SafeMath.sol b/packages/contracts/src/2.0.0/utils/SafeMath/SafeMath.sol
index e137f6ca5..e137f6ca5 100644
--- a/packages/contracts/src/contracts/current/utils/SafeMath/SafeMath.sol
+++ b/packages/contracts/src/2.0.0/utils/SafeMath/SafeMath.sol
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol
deleted file mode 100644
index b4780b52b..000000000
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC20Proxy.sol
+++ /dev/null
@@ -1,167 +0,0 @@
-/*
-
-  Copyright 2018 ZeroEx Intl.
-
-  Licensed under the Apache License, Version 2.0 (the "License");
-  you may not use this file except in compliance with the License.
-  You may obtain a copy of the License at
-
-    http://www.apache.org/licenses/LICENSE-2.0
-
-  Unless required by applicable law or agreed to in writing, software
-  distributed under the License is distributed on an "AS IS" BASIS,
-  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-  See the License for the specific language governing permissions and
-  limitations under the License.
-
-*/
-
-pragma solidity ^0.4.24;
-pragma experimental ABIEncoderV2;
-
-import "../../utils/LibBytes/LibBytes.sol";
-import "./interfaces/IAssetProxy.sol";
-import "./MixinAuthorizable.sol";
-
-contract ERC20Proxy is
-    IAssetProxy,
-    MixinAuthorizable
-{
-    // Id of this proxy.
-    bytes4 constant PROXY_ID = bytes4(keccak256("ERC20Token(address)"));
-    
-    /// @dev Internal version of `transferFrom`.
-    /// @param assetData Encoded byte array.
-    /// @param from Address to transfer asset from.
-    /// @param to Address to transfer asset to.
-    /// @param amount Amount of asset to transfer.
-    function transferFrom(
-        bytes assetData,
-        address from,
-        address to,
-        uint256 amount
-    )
-        external
-    {
-        require(
-            authorized[msg.sender],
-            "SENDER_NOT_AUTHORIZED"
-        );
-
-        // `transferFrom`.
-        // The function is marked `external`, so no abi decodeding is done for
-        // us. Instead, we expect the `calldata` memory to contain the
-        // following:
-        //
-        // | Area     | Offset | Length  | Contents                            |
-        // |----------|--------|---------|-------------------------------------|
-        // | Header   | 0      | 4       | function selector                   |
-        // | Params   |        | 4 * 32  | function parameters:                |
-        // |          | 4      |         |   1. offset to assetData (*)        |
-        // |          | 36     |         |   2. from                           |
-        // |          | 68     |         |   3. to                             |
-        // |          | 100    |         |   4. amount                         |
-        // | Data     |        |         | assetData:                          |
-        // |          | 132    | 32      | assetData Length                    |
-        // |          | 164    | **      | assetData Contents                  |
-        //
-        // (*): offset is computed from start of function parameters, so offset
-        //      by an additional 4 bytes in the calldata.
-        //
-        // WARNING: The ABIv2 specification allows additional padding between
-        //          the Params and Data section. This will result in a larger
-        //          offset to assetData.
-        
-        // Asset data itself is encoded as follows:
-        //
-        // | Area     | Offset | Length  | Contents                            |
-        // |----------|--------|---------|-------------------------------------|
-        // | Header   | 0      | 4       | function selector                   |
-        // | Params   |        | 1 * 32  | function parameters:                |
-        // |          | 4      | 12 + 20 |   1. token address                  |
-        
-        // Transfer tokens.
-        // We do a raw call so we can check the success separate
-        // from the return data.
-        // We construct calldata for the `token.transferFrom` ABI.
-        // The layout of this calldata is in the table below.
-        // 
-        // | Area     | Offset | Length  | Contents                            |
-        // |----------|--------|---------|-------------------------------------|
-        // | Header   | 0      | 4       | function selector                   |
-        // | Params   |        | 3 * 32  | function parameters:                |
-        // |          | 4      |         |   1. from                           |
-        // |          | 36     |         |   2. to                             |
-        // |          | 68     |         |   3. amount                         |
-        
-        assembly {
-            /////// Token contract address ///////
-            // The token address is found as follows:
-            // * It is stored at offset 4 in `assetData` contents.
-            // * This is stored at offset 32 from `assetData`.
-            // * The offset to `assetData` from Params is stored at offset
-            //   4 in calldata.
-            // * The offset of Params in calldata is 4.
-            // So we read location 4 and add 32 + 4 + 4 to it.
-            let token := calldataload(add(calldataload(4), 40))
-            
-            /////// Setup Header Area ///////
-            // This area holds the 4-byte `transferFrom` selector.
-            // Any trailing data in transferFromSelector will be
-            // overwritten in the next `mstore` call.
-            mstore(0, 0x23b872dd00000000000000000000000000000000000000000000000000000000)
-            
-            /////// Setup Params Area ///////
-            // We copy the fields `from`, `to` and `amount` in bulk
-            // from our own calldata to the new calldata.
-            calldatacopy(4, 36, 96)
-
-            /////// Call `token.transferFrom` using the calldata ///////
-            let success := call(
-                gas,            // forward all gas
-                token,          // call address of token contract
-                0,              // don't send any ETH
-                0,              // pointer to start of input
-                100,            // length of input
-                0,              // write output over input
-                32              // output size should be 32 bytes
-            )
-
-            /////// Check return data. ///////
-            // If there is no return data, we assume the token incorrectly
-            // does not return a bool. In this case we expect it to revert
-            // on failure, which was handled above.
-            // If the token does return data, we require that it is a single
-            // nonzero 32 bytes value.
-            // So the transfer succeeded if the call succeeded and either
-            // returned nothing, or returned a non-zero 32 byte value. 
-            success := and(success, or(
-                iszero(returndatasize),
-                and(
-                    eq(returndatasize, 32),
-                    gt(mload(0), 0)
-                )
-            ))
-            if success {
-                return(0, 0)
-            }
-            
-            // Revert with `Error("TRANSFER_FAILED")`
-            mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
-            mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
-            mstore(64, 0x0000000f5452414e534645525f4641494c454400000000000000000000000000)
-            mstore(96, 0)
-            revert(0, 100)
-        }
-    }
-
-    /// @dev Gets the proxy id associated with the proxy address.
-    /// @return Proxy id.
-    function getProxyId()
-        external
-        view
-        returns (bytes4)
-    {
-        return PROXY_ID;
-    }
-}
diff --git a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC721Proxy.sol b/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC721Proxy.sol
deleted file mode 100644
index 8d7cea717..000000000
--- a/packages/contracts/src/contracts/current/protocol/AssetProxy/ERC721Proxy.sol
+++ /dev/null
@@ -1,207 +0,0 @@
-/*
-
-  Copyright 2018 ZeroEx Intl.
-
-  Licensed under the Apache License, Version 2.0 (the "License");
-  you may not use this file except in compliance with the License.
-  You may obtain a copy of the License at
-
-    http://www.apache.org/licenses/LICENSE-2.0
-
-  Unless required by applicable law or agreed to in writing, software
-  distributed under the License is distributed on an "AS IS" BASIS,
-  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-  See the License for the specific language governing permissions and
-  limitations under the License.
-
-*/
-
-pragma solidity ^0.4.24;
-pragma experimental ABIEncoderV2;
-
-import "../../utils/LibBytes/LibBytes.sol";
-import "./interfaces/IAssetProxy.sol";
-import "./MixinAuthorizable.sol";
-
-contract ERC721Proxy is
-    IAssetProxy,
-    MixinAuthorizable
-{
-    // Id of this proxy.
-    bytes4 constant PROXY_ID = bytes4(keccak256("ERC721Token(address,uint256,bytes)"));
-
-    /// @dev Internal version of `transferFrom`.
-    /// @param assetData Encoded byte array.
-    /// @param from Address to transfer asset from.
-    /// @param to Address to transfer asset to.
-    /// @param amount Amount of asset to transfer.
-    function transferFrom(
-        bytes assetData,
-        address from,
-        address to,
-        uint256 amount
-    )
-        external
-    {
-        require(
-            authorized[msg.sender],
-            "SENDER_NOT_AUTHORIZED"
-        );
-    
-        // `transferFrom`.
-        // The function is marked `external`, so no abi decodeding is done for
-        // us. Instead, we expect the `calldata` memory to contain the
-        // following:
-        //
-        // | Area     | Offset | Length  | Contents                            |
-        // |----------|--------|---------|-------------------------------------|
-        // | Header   | 0      | 4       | function selector                   |
-        // | Params   |        | 4 * 32  | function parameters:                |
-        // |          | 4      |         |   1. offset to assetData (*)        |
-        // |          | 36     |         |   2. from                           |
-        // |          | 68     |         |   3. to                             |
-        // |          | 100    |         |   4. amount                         |
-        // | Data     |        |         | assetData:                          |
-        // |          | 132    | 32      | assetData Length                    |
-        // |          | 164    | **      | assetData Contents                  |
-        //
-        // (*): offset is computed from start of function parameters, so offset
-        //      by an additional 4 bytes in the calldata.
-        //
-        // WARNING: The ABIv2 specification allows additional padding between
-        //          the Params and Data section. This will result in a larger
-        //          offset to assetData.
-        
-        // Asset data itself is encoded as follows:
-        //
-        // | Area     | Offset | Length  | Contents                            |
-        // |----------|--------|---------|-------------------------------------|
-        // | Header   | 0      | 4       | function selector                   |
-        // | Params   |        | 3 * 32  | function parameters:                |
-        // |          | 4      | 12 + 20 |   1. token address                  |
-        // |          | 36     |         |   2. tokenId                        |
-        // |          | 68     |         |   3. offset to receiverData (*)     |
-        // | Data     |        |         | receiverData:                       |
-        // |          | 100    | 32      | receiverData Length                 |
-        // |          | 132    | **      | receiverData Contents               |
-        
-        // We construct calldata for the `token.safeTransferFrom` ABI.
-        // The layout of this calldata is in the table below.
-        // 
-        // | Area     | Offset | Length  | Contents                            |
-        // |----------|--------|---------|-------------------------------------|
-        // | Header   | 0      | 4       | function selector                   |
-        // | Params   |        | 4 * 32  | function parameters:                |
-        // |          | 4      |         |   1. from                           |
-        // |          | 36     |         |   2. to                             |
-        // |          | 68     |         |   3. tokenId                        |
-        // |          | 100    |         |   4. offset to receiverData (*)     |
-        // | Data     |        |         | receiverData:                       |
-        // |          | 132    | 32      | receiverData Length                 |
-        // |          | 164    | **      | receiverData Contents               |
-
-        assembly {
-            // There exists only 1 of each token.
-            // require(amount == 1, "INVALID_AMOUNT")
-            if sub(calldataload(100), 1) {
-                // Revert with `Error("INVALID_AMOUNT")`
-                mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
-                mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
-                mstore(64, 0x0000000e494e56414c49445f414d4f554e540000000000000000000000000000)
-                mstore(96, 0)
-                revert(0, 100)
-            }
-            
-            // Require assetData to be at least 132 bytes
-            let offset := calldataload(4)
-            if lt(calldataload(add(offset, 4)), 132) {
-                // Revert with `Error("LENGTH_GREATER_THAN_131_REQUIRED")`
-                mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
-                mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
-                mstore(64, 0x000000204c454e4754485f475245415445525f5448414e5f3133315f52455155)
-                mstore(96, 0x4952454400000000000000000000000000000000000000000000000000000000)
-                revert(0, 100)
-            }
-            
-            /////// Setup State ///////
-            // `cdStart` is the start of the calldata for
-            // `token.safeTransferFrom` (equal to free memory ptr).
-            let cdStart := mload(64)
-            // `dataAreaLength` is the total number of words
-            // needed to store `receiverData`
-            // As-per the ABI spec, this value is padded up to
-            // the nearest multiple of 32,
-            // and includes 32-bytes for length.
-            // It's calculated as folows:
-            //      - Unpadded length in bytes = `mload(receiverData) + 32`
-            //      - Add 31 to convert rounding down to rounding up.
-            //        Combined with the previous and this is `63`.
-            //      - Round down to nearest multiple of 32 by clearing
-            //        bits 0x1F. This is done with `and` and a mask.
-
-            /////// Setup Header Area ///////
-            // This area holds the 4-byte `transferFromSelector`.
-            // Any trailing data in transferFromSelector will be
-            // overwritten in the next `mstore` call.
-            mstore(cdStart, 0xb88d4fde00000000000000000000000000000000000000000000000000000000)
-            
-            /////// Setup Params Area ///////
-            // Each parameter is padded to 32-bytes.
-            // The entire Params Area is 128 bytes.
-            // Notes:
-            //   1. A 20-byte mask is applied to addresses
-            //      to zero-out the unused bytes.
-            //   2. The offset to `receiverData` is the length
-            //      of the Params Area (128 bytes).
-            
-            let length := calldataload(add(offset, 136))
-            let token := calldataload(add(offset, 40))
-            
-            // Round length up to multiple of 32
-            length := and(add(length, 31), 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFE0)
-            
-            // Copy `from` and `to`
-            calldatacopy(add(cdStart, 4), 36, 64)
-            
-            // TokenId
-            mstore(add(cdStart, 68), calldataload(add(offset, 72)))
-            
-            // Offset to receiverData
-            mstore(add(cdStart, 100), 128)
-            
-            // receiverData (including length)
-            calldatacopy(add(cdStart, 132), add(offset, 136), add(length, 32))
-            
-            /////// Call `token.safeTransferFrom` using the calldata ///////
-            let success := call(
-                gas,                    // forward all gas
-                token,                  // call address of token contract
-                0,                      // don't send any ETH
-                cdStart,                // pointer to start of input
-                add(length, 164),       // length of input
-                0,                      // write output to null
-                0                       // output size is 0 bytes
-            )
-            if success {
-                return(0, 0)
-            }
-            
-            // Revert with `Error("TRANSFER_FAILED")`
-            mstore(0, 0x08c379a000000000000000000000000000000000000000000000000000000000)
-            mstore(32, 0x0000002000000000000000000000000000000000000000000000000000000000)
-            mstore(64, 0x0000000f5452414e534645525f4641494c454400000000000000000000000000)
-            mstore(96, 0)
-            revert(0, 100)
-        }
-    }
-
-    /// @dev Gets the proxy id associated with the proxy address.
-    /// @return Proxy id.
-    function getProxyId()
-        external
-        view
-        returns (bytes4)
-    {
-        return PROXY_ID;
-    }
-}
diff --git a/packages/contracts/src/utils/artifacts.ts b/packages/contracts/src/utils/artifacts.ts
deleted file mode 100644
index d58e7973c..000000000
--- a/packages/contracts/src/utils/artifacts.ts
+++ /dev/null
@@ -1,49 +0,0 @@
-import { ContractArtifact } from '@0xproject/sol-compiler';
-
-import * as AssetProxyOwner from '../artifacts/AssetProxyOwner.json';
-import * as DummyERC20Token from '../artifacts/DummyERC20Token.json';
-import * as DummyERC721Receiver from '../artifacts/DummyERC721Receiver.json';
-import * as DummyERC721Token from '../artifacts/DummyERC721Token.json';
-import * as ERC20Proxy from '../artifacts/ERC20Proxy.json';
-import * as ERC721Proxy from '../artifacts/ERC721Proxy.json';
-import * as Exchange from '../artifacts/Exchange.json';
-import * as ExchangeWrapper from '../artifacts/ExchangeWrapper.json';
-import * as MixinAuthorizable from '../artifacts/MixinAuthorizable.json';
-import * as MultiSigWallet from '../artifacts/MultiSigWallet.json';
-import * as MultiSigWalletWithTimeLock from '../artifacts/MultiSigWalletWithTimeLock.json';
-import * as TestAssetProxyDispatcher from '../artifacts/TestAssetProxyDispatcher.json';
-import * as TestAssetProxyOwner from '../artifacts/TestAssetProxyOwner.json';
-import * as TestLibBytes from '../artifacts/TestLibBytes.json';
-import * as TestLibs from '../artifacts/TestLibs.json';
-import * as TestSignatureValidator from '../artifacts/TestSignatureValidator.json';
-import * as TestValidator from '../artifacts/TestValidator.json';
-import * as TestWallet from '../artifacts/TestWallet.json';
-import * as TokenRegistry from '../artifacts/TokenRegistry.json';
-import * as EtherToken from '../artifacts/WETH9.json';
-import * as Whitelist from '../artifacts/Whitelist.json';
-import * as ZRX from '../artifacts/ZRXToken.json';
-
-export const artifacts = {
-    AssetProxyOwner: (AssetProxyOwner as any) as ContractArtifact,
-    DummyERC20Token: (DummyERC20Token as any) as ContractArtifact,
-    DummyERC721Receiver: (DummyERC721Receiver as any) as ContractArtifact,
-    DummyERC721Token: (DummyERC721Token as any) as ContractArtifact,
-    ERC20Proxy: (ERC20Proxy as any) as ContractArtifact,
-    ERC721Proxy: (ERC721Proxy as any) as ContractArtifact,
-    Exchange: (Exchange as any) as ContractArtifact,
-    ExchangeWrapper: (ExchangeWrapper as any) as ContractArtifact,
-    EtherToken: (EtherToken as any) as ContractArtifact,
-    MixinAuthorizable: (MixinAuthorizable as any) as ContractArtifact,
-    MultiSigWallet: (MultiSigWallet as any) as ContractArtifact,
-    MultiSigWalletWithTimeLock: (MultiSigWalletWithTimeLock as any) as ContractArtifact,
-    TestAssetProxyOwner: (TestAssetProxyOwner as any) as ContractArtifact,
-    TestAssetProxyDispatcher: (TestAssetProxyDispatcher as any) as ContractArtifact,
-    TestLibBytes: (TestLibBytes as any) as ContractArtifact,
-    TestLibs: (TestLibs as any) as ContractArtifact,
-    TestSignatureValidator: (TestSignatureValidator as any) as ContractArtifact,
-    TestValidator: (TestValidator as any) as ContractArtifact,
-    TestWallet: (TestWallet as any) as ContractArtifact,
-    TokenRegistry: (TokenRegistry as any) as ContractArtifact,
-    Whitelist: (Whitelist as any) as ContractArtifact,
-    ZRX: (ZRX as any) as ContractArtifact,
-};
diff --git a/packages/contracts/test/asset_proxy/authorizable.ts b/packages/contracts/test/asset_proxy/authorizable.ts
index 8c9d0495d..5a0586c28 100644
--- a/packages/contracts/test/asset_proxy/authorizable.ts
+++ b/packages/contracts/test/asset_proxy/authorizable.ts
@@ -3,12 +3,12 @@ import { RevertReason } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import * as chai from 'chai';
 
-import { MixinAuthorizableContract } from '../../src/generated_contract_wrappers/mixin_authorizable';
-import { artifacts } from '../../src/utils/artifacts';
-import { expectRevertReasonOrAlwaysFailingTransactionAsync } from '../../src/utils/assertions';
-import { chaiSetup } from '../../src/utils/chai_setup';
-import { constants } from '../../src/utils/constants';
-import { provider, txDefaults, web3Wrapper } from '../../src/utils/web3_wrapper';
+import { MixinAuthorizableContract } from '../../generated_contract_wrappers/mixin_authorizable';
+import { artifacts } from '../utils/artifacts';
+import { expectRevertReasonOrAlwaysFailingTransactionAsync } from '../utils/assertions';
+import { chaiSetup } from '../utils/chai_setup';
+import { constants } from '../utils/constants';
+import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
 
 chaiSetup.configure();
 const expect = chai.expect;
diff --git a/packages/contracts/test/asset_proxy/proxies.ts b/packages/contracts/test/asset_proxy/proxies.ts
index 39121d95c..fc1e53352 100644
--- a/packages/contracts/test/asset_proxy/proxies.ts
+++ b/packages/contracts/test/asset_proxy/proxies.ts
@@ -7,26 +7,32 @@ 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 { DummyERC20TokenContract } from '../../generated_contract_wrappers/dummy_e_r_c20_token';
 import {
     DummyERC721ReceiverContract,
     TokenReceivedContractEventArgs,
-} from '../../src/generated_contract_wrappers/dummy_e_r_c721_receiver';
-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 { artifacts } from '../../src/utils/artifacts';
-import { expectRevertReasonOrAlwaysFailingTransactionAsync } from '../../src/utils/assertions';
-import { chaiSetup } from '../../src/utils/chai_setup';
-import { constants } from '../../src/utils/constants';
-import { ERC20Wrapper } from '../../src/utils/erc20_wrapper';
-import { ERC721Wrapper } from '../../src/utils/erc721_wrapper';
-import { LogDecoder } from '../../src/utils/log_decoder';
-import { provider, txDefaults, web3Wrapper } from '../../src/utils/web3_wrapper';
+} from '../../generated_contract_wrappers/dummy_e_r_c721_receiver';
+import { DummyERC721TokenContract } from '../../generated_contract_wrappers/dummy_e_r_c721_token';
+import { ERC20ProxyContract } from '../../generated_contract_wrappers/e_r_c20_proxy';
+import { ERC721ProxyContract } from '../../generated_contract_wrappers/e_r_c721_proxy';
+import { IAssetProxyContract } from '../../generated_contract_wrappers/i_asset_proxy';
+import { artifacts } from '../utils/artifacts';
+import { expectRevertReasonOrAlwaysFailingTransactionAsync } from '../utils/assertions';
+import { chaiSetup } from '../utils/chai_setup';
+import { constants } from '../utils/constants';
+import { ERC20Wrapper } from '../utils/erc20_wrapper';
+import { ERC721Wrapper } from '../utils/erc721_wrapper';
+import { LogDecoder } from '../utils/log_decoder';
+import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
 
 chaiSetup.configure();
 const expect = chai.expect;
 const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
+const assetProxyInterface = new IAssetProxyContract(
+    artifacts.IAssetProxy.compilerOutput.abi,
+    constants.NULL_ADDRESS,
+    provider,
+);
 
 // tslint:disable:no-unnecessary-type-assertion
 describe('Asset Transfer Proxies', () => {
@@ -105,14 +111,18 @@ describe('Asset Transfer Proxies', () => {
                 // Perform a transfer from makerAddress to takerAddress
                 const erc20Balances = await erc20Wrapper.getBalancesAsync();
                 const amount = new BigNumber(10);
+                const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
+                    encodedAssetData,
+                    makerAddress,
+                    takerAddress,
+                    amount,
+                );
                 await web3Wrapper.awaitTransactionSuccessAsync(
-                    await erc20Proxy.transferFrom.sendTransactionAsync(
-                        encodedAssetData,
-                        makerAddress,
-                        takerAddress,
-                        amount,
-                        { from: exchangeAddress },
-                    ),
+                    await web3Wrapper.sendTransactionAsync({
+                        to: erc20Proxy.address,
+                        data,
+                        from: exchangeAddress,
+                    }),
                     constants.AWAIT_TRANSACTION_MINED_MS,
                 );
                 // Verify transfer was successful
@@ -131,14 +141,18 @@ describe('Asset Transfer Proxies', () => {
                 // Perform a transfer from makerAddress to takerAddress
                 const erc20Balances = await erc20Wrapper.getBalancesAsync();
                 const amount = new BigNumber(0);
+                const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
+                    encodedAssetData,
+                    makerAddress,
+                    takerAddress,
+                    amount,
+                );
                 await web3Wrapper.awaitTransactionSuccessAsync(
-                    await erc20Proxy.transferFrom.sendTransactionAsync(
-                        encodedAssetData,
-                        makerAddress,
-                        takerAddress,
-                        amount,
-                        { from: exchangeAddress },
-                    ),
+                    await web3Wrapper.sendTransactionAsync({
+                        to: erc20Proxy.address,
+                        data,
+                        from: exchangeAddress,
+                    }),
                     constants.AWAIT_TRANSACTION_MINED_MS,
                 );
                 // Verify transfer was successful
@@ -156,7 +170,13 @@ describe('Asset Transfer Proxies', () => {
                 const encodedAssetData = assetProxyUtils.encodeERC20AssetData(zrxToken.address);
                 // Create allowance less than transfer amount. Set allowance on proxy.
                 const allowance = new BigNumber(0);
-                const transferAmount = new BigNumber(10);
+                const amount = new BigNumber(10);
+                const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
+                    encodedAssetData,
+                    makerAddress,
+                    takerAddress,
+                    amount,
+                );
                 await web3Wrapper.awaitTransactionSuccessAsync(
                     await zrxToken.approve.sendTransactionAsync(erc20Proxy.address, allowance, {
                         from: makerAddress,
@@ -165,13 +185,11 @@ describe('Asset Transfer Proxies', () => {
                 );
                 // Perform a transfer; expect this to fail.
                 return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                    erc20Proxy.transferFrom.sendTransactionAsync(
-                        encodedAssetData,
-                        makerAddress,
-                        takerAddress,
-                        transferAmount,
-                        { from: exchangeAddress },
-                    ),
+                    web3Wrapper.sendTransactionAsync({
+                        to: erc20Proxy.address,
+                        data,
+                        from: exchangeAddress,
+                    }),
                     RevertReason.TransferFailed,
                 );
             });
@@ -179,11 +197,18 @@ describe('Asset Transfer Proxies', () => {
             it('should throw if requesting address is not authorized', async () => {
                 // Construct ERC20 asset data
                 const encodedAssetData = assetProxyUtils.encodeERC20AssetData(zrxToken.address);
-
                 // Perform a transfer from makerAddress to takerAddress
                 const amount = new BigNumber(10);
+                const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
+                    encodedAssetData,
+                    makerAddress,
+                    takerAddress,
+                    amount,
+                );
                 return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                    erc20Proxy.transferFrom.sendTransactionAsync(encodedAssetData, makerAddress, takerAddress, amount, {
+                    web3Wrapper.sendTransactionAsync({
+                        to: erc20Proxy.address,
+                        data,
                         from: notAuthorized,
                     }),
                     RevertReason.SenderNotAuthorized,
@@ -208,14 +233,18 @@ describe('Asset Transfer Proxies', () => {
                 expect(ownerMakerAsset).to.be.bignumber.equal(makerAddress);
                 // Perform a transfer from makerAddress to takerAddress
                 const amount = new BigNumber(1);
+                const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
+                    encodedAssetData,
+                    makerAddress,
+                    takerAddress,
+                    amount,
+                );
                 await web3Wrapper.awaitTransactionSuccessAsync(
-                    await erc721Proxy.transferFrom.sendTransactionAsync(
-                        encodedAssetData,
-                        makerAddress,
-                        takerAddress,
-                        amount,
-                        { from: exchangeAddress },
-                    ),
+                    await web3Wrapper.sendTransactionAsync({
+                        to: erc721Proxy.address,
+                        data,
+                        from: exchangeAddress,
+                    }),
                     constants.AWAIT_TRANSACTION_MINED_MS,
                 );
                 // Verify transfer was successful
@@ -231,17 +260,21 @@ describe('Asset Transfer Proxies', () => {
                 expect(ownerMakerAsset).to.be.bignumber.equal(makerAddress);
                 // Perform a transfer from makerAddress to takerAddress
                 const amount = new BigNumber(1);
-                const txHash = await erc721Proxy.transferFrom.sendTransactionAsync(
+                const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
                     encodedAssetData,
                     makerAddress,
                     erc721Receiver.address,
                     amount,
-                    { from: exchangeAddress },
                 );
-                await web3Wrapper.awaitTransactionSuccessAsync(txHash, constants.AWAIT_TRANSACTION_MINED_MS);
-                // Parse transaction logs
                 const logDecoder = new LogDecoder(web3Wrapper, erc721Receiver.address);
-                const tx = await logDecoder.getTxWithDecodedLogsAsync(txHash);
+                const tx = await logDecoder.getTxWithDecodedLogsAsync(
+                    await web3Wrapper.sendTransactionAsync({
+                        to: erc721Proxy.address,
+                        data,
+                        from: exchangeAddress,
+                        gas: constants.TRANSFER_FROM_GAS,
+                    }),
+                );
                 // Verify that no log was emitted by erc721 receiver
                 expect(tx.logs.length).to.be.equal(1);
                 const tokenReceivedLog = tx.logs[0] as LogWithDecodedArgs<TokenReceivedContractEventArgs>;
@@ -266,17 +299,21 @@ describe('Asset Transfer Proxies', () => {
                 expect(ownerMakerAsset).to.be.bignumber.equal(makerAddress);
                 // Perform a transfer from makerAddress to takerAddress
                 const amount = new BigNumber(1);
-                const txHash = await erc721Proxy.transferFrom.sendTransactionAsync(
+                const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
                     encodedAssetData,
                     makerAddress,
                     erc721Receiver.address,
                     amount,
-                    { from: exchangeAddress },
                 );
-                await web3Wrapper.awaitTransactionSuccessAsync(txHash, constants.AWAIT_TRANSACTION_MINED_MS);
-                // Parse transaction logs
                 const logDecoder = new LogDecoder(web3Wrapper, erc721Receiver.address);
-                const tx = await logDecoder.getTxWithDecodedLogsAsync(txHash);
+                const tx = await logDecoder.getTxWithDecodedLogsAsync(
+                    await web3Wrapper.sendTransactionAsync({
+                        to: erc721Proxy.address,
+                        data,
+                        from: exchangeAddress,
+                        gas: constants.TRANSFER_FROM_GAS,
+                    }),
+                );
                 // Validate log emitted by erc721 receiver
                 expect(tx.logs.length).to.be.equal(1);
                 const tokenReceivedLog = tx.logs[0] as LogWithDecodedArgs<TokenReceivedContractEventArgs>;
@@ -301,14 +338,19 @@ describe('Asset Transfer Proxies', () => {
                 expect(ownerMakerAsset).to.be.bignumber.equal(makerAddress);
                 // Perform a transfer from makerAddress to takerAddress
                 const amount = new BigNumber(1);
+                const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
+                    encodedAssetData,
+                    makerAddress,
+                    erc20Proxy.address, // the ERC20 proxy does not have an ERC721 receiver
+                    amount,
+                );
                 return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                    erc721Proxy.transferFrom.sendTransactionAsync(
-                        encodedAssetData,
-                        makerAddress,
-                        erc20Proxy.address, // the ERC20 proxy does not have an ERC721 receiver
-                        amount,
-                        { from: exchangeAddress },
-                    ),
+                    web3Wrapper.sendTransactionAsync({
+                        to: erc721Proxy.address,
+                        data,
+                        from: exchangeAddress,
+                        gas: constants.TRANSFER_FROM_GAS,
+                    }),
                     RevertReason.TransferFailed,
                 );
             });
@@ -321,14 +363,18 @@ describe('Asset Transfer Proxies', () => {
                 expect(ownerMakerAsset).to.be.bignumber.equal(makerAddress);
                 // Perform a transfer from makerAddress to takerAddress
                 const amount = new BigNumber(0);
+                const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
+                    encodedAssetData,
+                    makerAddress,
+                    takerAddress,
+                    amount,
+                );
                 return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                    erc721Proxy.transferFrom.sendTransactionAsync(
-                        encodedAssetData,
-                        makerAddress,
-                        takerAddress,
-                        amount,
-                        { from: exchangeAddress },
-                    ),
+                    web3Wrapper.sendTransactionAsync({
+                        to: erc721Proxy.address,
+                        data,
+                        from: exchangeAddress,
+                    }),
                     RevertReason.InvalidAmount,
                 );
             });
@@ -341,14 +387,18 @@ describe('Asset Transfer Proxies', () => {
                 expect(ownerMakerAsset).to.be.bignumber.equal(makerAddress);
                 // Perform a transfer from makerAddress to takerAddress
                 const amount = new BigNumber(500);
+                const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
+                    encodedAssetData,
+                    makerAddress,
+                    takerAddress,
+                    amount,
+                );
                 return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                    erc721Proxy.transferFrom.sendTransactionAsync(
-                        encodedAssetData,
-                        makerAddress,
-                        takerAddress,
-                        amount,
-                        { from: exchangeAddress },
-                    ),
+                    web3Wrapper.sendTransactionAsync({
+                        to: erc721Proxy.address,
+                        data,
+                        from: exchangeAddress,
+                    }),
                     RevertReason.InvalidAmount,
                 );
             });
@@ -358,15 +408,23 @@ describe('Asset Transfer Proxies', () => {
                 const encodedAssetData = assetProxyUtils.encodeERC721AssetData(erc721Token.address, erc721MakerTokenId);
                 // Remove transfer approval for makerAddress.
                 await web3Wrapper.awaitTransactionSuccessAsync(
-                    await erc721Token.setApprovalForAll.sendTransactionAsync(erc721Proxy.address, false, {
+                    await erc721Token.approve.sendTransactionAsync(constants.NULL_ADDRESS, erc721MakerTokenId, {
                         from: makerAddress,
                     }),
                     constants.AWAIT_TRANSACTION_MINED_MS,
                 );
                 // Perform a transfer; expect this to fail.
                 const amount = new BigNumber(1);
+                const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
+                    encodedAssetData,
+                    makerAddress,
+                    takerAddress,
+                    amount,
+                );
                 return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                    erc20Proxy.transferFrom.sendTransactionAsync(encodedAssetData, makerAddress, takerAddress, amount, {
+                    web3Wrapper.sendTransactionAsync({
+                        to: erc721Proxy.address,
+                        data,
                         from: exchangeAddress,
                     }),
                     RevertReason.TransferFailed,
@@ -378,14 +436,18 @@ describe('Asset Transfer Proxies', () => {
                 const encodedAssetData = assetProxyUtils.encodeERC721AssetData(erc721Token.address, erc721MakerTokenId);
                 // Perform a transfer from makerAddress to takerAddress
                 const amount = new BigNumber(1);
+                const data = assetProxyInterface.transferFrom.getABIEncodedTransactionData(
+                    encodedAssetData,
+                    makerAddress,
+                    takerAddress,
+                    amount,
+                );
                 return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                    erc721Proxy.transferFrom.sendTransactionAsync(
-                        encodedAssetData,
-                        makerAddress,
-                        takerAddress,
-                        amount,
-                        { from: notAuthorized },
-                    ),
+                    web3Wrapper.sendTransactionAsync({
+                        to: erc721Proxy.address,
+                        data,
+                        from: notAuthorized,
+                    }),
                     RevertReason.SenderNotAuthorized,
                 );
             });
diff --git a/packages/contracts/test/exchange/core.ts b/packages/contracts/test/exchange/core.ts
index 0c7381aac..db56623f9 100644
--- a/packages/contracts/test/exchange/core.ts
+++ b/packages/contracts/test/exchange/core.ts
@@ -1,6 +1,6 @@
 import { BlockchainLifecycle } from '@0xproject/dev-utils';
 import { assetProxyUtils, orderHashUtils } from '@0xproject/order-utils';
-import { AssetProxyId, RevertReason, SignedOrder } from '@0xproject/types';
+import { RevertReason, SignedOrder } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import * as chai from 'chai';
@@ -8,21 +8,21 @@ 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 } 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';
-import { constants } from '../../src/utils/constants';
-import { ERC20Wrapper } from '../../src/utils/erc20_wrapper';
-import { ERC721Wrapper } from '../../src/utils/erc721_wrapper';
-import { ExchangeWrapper } from '../../src/utils/exchange_wrapper';
-import { OrderFactory } from '../../src/utils/order_factory';
-import { ERC20BalancesByOwner } from '../../src/utils/types';
-import { provider, txDefaults, web3Wrapper } from '../../src/utils/web3_wrapper';
+import { DummyERC20TokenContract } from '../../generated_contract_wrappers/dummy_e_r_c20_token';
+import { DummyERC721TokenContract } from '../../generated_contract_wrappers/dummy_e_r_c721_token';
+import { ERC20ProxyContract } from '../../generated_contract_wrappers/e_r_c20_proxy';
+import { ERC721ProxyContract } from '../../generated_contract_wrappers/e_r_c721_proxy';
+import { CancelContractEventArgs, ExchangeContract } from '../../generated_contract_wrappers/exchange';
+import { artifacts } from '../utils/artifacts';
+import { expectRevertReasonOrAlwaysFailingTransactionAsync } from '../utils/assertions';
+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 { OrderFactory } from '../utils/order_factory';
+import { ERC20BalancesByOwner } from '../utils/types';
+import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
 
 chaiSetup.configure();
 const expect = chai.expect;
@@ -90,8 +90,8 @@ describe('Exchange core', () => {
             assetProxyUtils.encodeERC20AssetData(zrxToken.address),
         );
         exchangeWrapper = new ExchangeWrapper(exchange, provider);
-        await exchangeWrapper.registerAssetProxyAsync(AssetProxyId.ERC20, erc20Proxy.address, owner);
-        await exchangeWrapper.registerAssetProxyAsync(AssetProxyId.ERC721, erc721Proxy.address, owner);
+        await exchangeWrapper.registerAssetProxyAsync(erc20Proxy.address, owner);
+        await exchangeWrapper.registerAssetProxyAsync(erc721Proxy.address, owner);
 
         await web3Wrapper.awaitTransactionSuccessAsync(
             await erc20Proxy.addAuthorizedAddress.sendTransactionAsync(exchange.address, {
diff --git a/packages/contracts/test/exchange/dispatcher.ts b/packages/contracts/test/exchange/dispatcher.ts
index e35cca845..afbf958d9 100644
--- a/packages/contracts/test/exchange/dispatcher.ts
+++ b/packages/contracts/test/exchange/dispatcher.ts
@@ -3,24 +3,29 @@ import { assetProxyUtils } from '@0xproject/order-utils';
 import { AssetProxyId, RevertReason } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import * as chai from 'chai';
+import { LogWithDecodedArgs } from 'ethereum-types';
 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';
-import { ERC721ProxyContract } from '../../src/generated_contract_wrappers/e_r_c721_proxy';
-import { TestAssetProxyDispatcherContract } from '../../src/generated_contract_wrappers/test_asset_proxy_dispatcher';
-import { artifacts } from '../../src/utils/artifacts';
-import { expectRevertReasonOrAlwaysFailingTransactionAsync } from '../../src/utils/assertions';
-import { chaiSetup } from '../../src/utils/chai_setup';
-import { constants } from '../../src/utils/constants';
-import { ERC20Wrapper } from '../../src/utils/erc20_wrapper';
-import { ERC721Wrapper } from '../../src/utils/erc721_wrapper';
-import { provider, txDefaults, web3Wrapper } from '../../src/utils/web3_wrapper';
+import { DummyERC20TokenContract } from '../../generated_contract_wrappers/dummy_e_r_c20_token';
+import { ERC20ProxyContract } from '../../generated_contract_wrappers/e_r_c20_proxy';
+import { ERC721ProxyContract } from '../../generated_contract_wrappers/e_r_c721_proxy';
+import {
+    AssetProxyRegisteredContractEventArgs,
+    TestAssetProxyDispatcherContract,
+} from '../../generated_contract_wrappers/test_asset_proxy_dispatcher';
+import { artifacts } from '../utils/artifacts';
+import { expectRevertReasonOrAlwaysFailingTransactionAsync } from '../utils/assertions';
+import { chaiSetup } from '../utils/chai_setup';
+import { constants } from '../utils/constants';
+import { ERC20Wrapper } from '../utils/erc20_wrapper';
+import { ERC721Wrapper } from '../utils/erc721_wrapper';
+import { LogDecoder } from '../utils/log_decoder';
+import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
 
 chaiSetup.configure();
 const expect = chai.expect;
 const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
-
+// tslint:disable:no-unnecessary-type-assertion
 describe('AssetProxyDispatcher', () => {
     let owner: string;
     let notOwner: string;
@@ -82,14 +87,8 @@ describe('AssetProxyDispatcher', () => {
     });
     describe('registerAssetProxy', () => {
         it('should record proxy upon registration', async () => {
-            const prevProxyAddress = constants.NULL_ADDRESS;
             await web3Wrapper.awaitTransactionSuccessAsync(
-                await assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(
-                    AssetProxyId.ERC20,
-                    erc20Proxy.address,
-                    prevProxyAddress,
-                    { from: owner },
-                ),
+                await assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(erc20Proxy.address, { from: owner }),
                 constants.AWAIT_TRANSACTION_MINED_MS,
             );
             const proxyAddress = await assetProxyDispatcher.getAssetProxy.callAsync(AssetProxyId.ERC20);
@@ -98,46 +97,30 @@ describe('AssetProxyDispatcher', () => {
 
         it('should be able to record multiple proxies', async () => {
             // Record first proxy
-            const prevERC20ProxyAddress = constants.NULL_ADDRESS;
             await web3Wrapper.awaitTransactionSuccessAsync(
-                await assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(
-                    AssetProxyId.ERC20,
-                    erc20Proxy.address,
-                    prevERC20ProxyAddress,
-                    { from: owner },
-                ),
+                await assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(erc20Proxy.address, { from: owner }),
                 constants.AWAIT_TRANSACTION_MINED_MS,
             );
             let proxyAddress = await assetProxyDispatcher.getAssetProxy.callAsync(AssetProxyId.ERC20);
             expect(proxyAddress).to.be.equal(erc20Proxy.address);
             // Record another proxy
-            const prevERC721ProxyAddress = constants.NULL_ADDRESS;
             await web3Wrapper.awaitTransactionSuccessAsync(
-                await assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(
-                    AssetProxyId.ERC721,
-                    erc721Proxy.address,
-                    prevERC721ProxyAddress,
-                    { from: owner },
-                ),
+                await assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(erc721Proxy.address, {
+                    from: owner,
+                }),
                 constants.AWAIT_TRANSACTION_MINED_MS,
             );
             proxyAddress = await assetProxyDispatcher.getAssetProxy.callAsync(AssetProxyId.ERC721);
             expect(proxyAddress).to.be.equal(erc721Proxy.address);
         });
 
-        it('should replace proxy address upon re-registration', async () => {
+        it('should throw if a proxy with the same id is already registered', async () => {
             // Initial registration
-            const prevProxyAddress = constants.NULL_ADDRESS;
             await web3Wrapper.awaitTransactionSuccessAsync(
-                await assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(
-                    AssetProxyId.ERC20,
-                    erc20Proxy.address,
-                    prevProxyAddress,
-                    { from: owner },
-                ),
+                await assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(erc20Proxy.address, { from: owner }),
                 constants.AWAIT_TRANSACTION_MINED_MS,
             );
-            let proxyAddress = await assetProxyDispatcher.getAssetProxy.callAsync(AssetProxyId.ERC20);
+            const proxyAddress = await assetProxyDispatcher.getAssetProxy.callAsync(AssetProxyId.ERC20);
             expect(proxyAddress).to.be.equal(erc20Proxy.address);
             // Deploy a new version of the ERC20 Transfer Proxy contract
             const newErc20TransferProxy = await ERC20ProxyContract.deployFrom0xArtifactAsync(
@@ -146,114 +129,37 @@ describe('AssetProxyDispatcher', () => {
                 txDefaults,
             );
             // Register new ERC20 Transfer Proxy contract
-            const newAddress = newErc20TransferProxy.address;
-            const currentAddress = erc20Proxy.address;
-            await web3Wrapper.awaitTransactionSuccessAsync(
-                await assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(
-                    AssetProxyId.ERC20,
-                    newAddress,
-                    currentAddress,
-                    { from: owner },
-                ),
-                constants.AWAIT_TRANSACTION_MINED_MS,
-            );
-            // Verify new asset proxy has replaced initial version
-            proxyAddress = await assetProxyDispatcher.getAssetProxy.callAsync(AssetProxyId.ERC20);
-            expect(proxyAddress).to.be.equal(newAddress);
-        });
-
-        it('should throw if registering with incorrect "currentAssetProxyAddress" field', async () => {
-            // Initial registration
-            const prevProxyAddress = constants.NULL_ADDRESS;
-            await web3Wrapper.awaitTransactionSuccessAsync(
-                await assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(
-                    AssetProxyId.ERC20,
-                    erc20Proxy.address,
-                    prevProxyAddress,
-                    { from: owner },
-                ),
-                constants.AWAIT_TRANSACTION_MINED_MS,
-            );
-            const proxyAddress = await assetProxyDispatcher.getAssetProxy.callAsync(AssetProxyId.ERC20);
-            expect(proxyAddress).to.be.equal(erc20Proxy.address);
-            // The following transaction will throw because the currentAddress is no longer constants.NULL_ADDRESS
             return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(
-                    AssetProxyId.ERC20,
-                    erc20Proxy.address,
-                    constants.NULL_ADDRESS,
-                    { from: owner },
-                ),
-                RevertReason.AssetProxyMismatch,
+                assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(newErc20TransferProxy.address, {
+                    from: owner,
+                }),
+                RevertReason.AssetProxyAlreadyExists,
             );
         });
 
-        it('should be able to reset proxy address to NULL', async () => {
-            // Initial registration
-            const prevProxyAddress = constants.NULL_ADDRESS;
-            await web3Wrapper.awaitTransactionSuccessAsync(
-                await assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(
-                    AssetProxyId.ERC20,
-                    erc20Proxy.address,
-                    prevProxyAddress,
-                    { from: owner },
-                ),
-                constants.AWAIT_TRANSACTION_MINED_MS,
-            );
-            const proxyAddress = await assetProxyDispatcher.getAssetProxy.callAsync(AssetProxyId.ERC20);
-            expect(proxyAddress).to.be.equal(erc20Proxy.address);
-            // The following transaction will reset the proxy address
-            const newProxyAddress = constants.NULL_ADDRESS;
-            await web3Wrapper.awaitTransactionSuccessAsync(
-                await assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(
-                    AssetProxyId.ERC20,
-                    newProxyAddress,
-                    erc20Proxy.address,
-                    { from: owner },
-                ),
-                constants.AWAIT_TRANSACTION_MINED_MS,
-            );
-            const finalProxyAddress = await assetProxyDispatcher.getAssetProxy.callAsync(AssetProxyId.ERC20);
-            expect(finalProxyAddress).to.be.equal(newProxyAddress);
-        });
-
         it('should throw if requesting address is not owner', async () => {
-            const prevProxyAddress = constants.NULL_ADDRESS;
             return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(
-                    AssetProxyId.ERC20,
-                    erc20Proxy.address,
-                    prevProxyAddress,
-                    { from: notOwner },
-                ),
+                assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(erc20Proxy.address, { from: notOwner }),
                 RevertReason.OnlyContractOwner,
             );
         });
 
-        it('should throw if attempting to register a proxy to the incorrect id', async () => {
-            const prevProxyAddress = constants.NULL_ADDRESS;
-            return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(
-                    AssetProxyId.ERC721,
-                    erc20Proxy.address,
-                    prevProxyAddress,
-                    { from: owner },
-                ),
-                RevertReason.AssetProxyIdMismatch,
+        it('should log an event with correct arguments when an asset proxy is registered', async () => {
+            const logDecoder = new LogDecoder(web3Wrapper, assetProxyDispatcher.address);
+            const txReceipt = await logDecoder.getTxWithDecodedLogsAsync(
+                await assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(erc20Proxy.address, { from: owner }),
             );
+            const logs = txReceipt.logs;
+            const log = logs[0] as LogWithDecodedArgs<AssetProxyRegisteredContractEventArgs>;
+            expect(log.args.id).to.equal(AssetProxyId.ERC20);
+            expect(log.args.assetProxy).to.equal(erc20Proxy.address);
         });
     });
 
     describe('getAssetProxy', () => {
         it('should return correct address of registered proxy', async () => {
-            const prevProxyAddress = constants.NULL_ADDRESS;
             await web3Wrapper.awaitTransactionSuccessAsync(
-                await assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(
-                    AssetProxyId.ERC20,
-                    erc20Proxy.address,
-                    prevProxyAddress,
-                    { from: owner },
-                ),
+                await assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(erc20Proxy.address, { from: owner }),
                 constants.AWAIT_TRANSACTION_MINED_MS,
             );
             const proxyAddress = await assetProxyDispatcher.getAssetProxy.callAsync(AssetProxyId.ERC20);
@@ -269,14 +175,8 @@ describe('AssetProxyDispatcher', () => {
     describe('dispatchTransferFrom', () => {
         it('should dispatch transfer to registered proxy', async () => {
             // Register ERC20 proxy
-            const prevProxyAddress = constants.NULL_ADDRESS;
             await web3Wrapper.awaitTransactionSuccessAsync(
-                await assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(
-                    AssetProxyId.ERC20,
-                    erc20Proxy.address,
-                    prevProxyAddress,
-                    { from: owner },
-                ),
+                await assetProxyDispatcher.registerAssetProxy.sendTransactionAsync(erc20Proxy.address, { from: owner }),
                 constants.AWAIT_TRANSACTION_MINED_MS,
             );
             // Construct metadata for ERC20 proxy
@@ -323,3 +223,4 @@ describe('AssetProxyDispatcher', () => {
         });
     });
 });
+// tslint:enable:no-unnecessary-type-assertion
diff --git a/packages/contracts/test/exchange/fill_order.ts b/packages/contracts/test/exchange/fill_order.ts
index 7bf12809a..21d86622b 100644
--- a/packages/contracts/test/exchange/fill_order.ts
+++ b/packages/contracts/test/exchange/fill_order.ts
@@ -1,10 +1,8 @@
 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 { chaiSetup } from '../utils/chai_setup';
+import { CoreCombinatorialUtils, coreCombinatorialUtilsFactoryAsync } from '../utils/core_combinatorial_utils';
 import {
     AllowanceAmountScenario,
     AssetDataScenario,
@@ -15,7 +13,8 @@ import {
     OrderAssetAmountScenario,
     TakerAssetFillAmountScenario,
     TakerScenario,
-} from '../../src/utils/types';
+} from '../utils/types';
+import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
 
 chaiSetup.configure();
 const blockchainLifecycle = new BlockchainLifecycle(web3Wrapper);
diff --git a/packages/contracts/test/exchange/libs.ts b/packages/contracts/test/exchange/libs.ts
index c08001198..6ded6329c 100644
--- a/packages/contracts/test/exchange/libs.ts
+++ b/packages/contracts/test/exchange/libs.ts
@@ -4,13 +4,13 @@ import { SignedOrder } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import * as chai from 'chai';
 
-import { TestLibsContract } from '../../src/generated_contract_wrappers/test_libs';
-import { addressUtils } from '../../src/utils/address_utils';
-import { artifacts } from '../../src/utils/artifacts';
-import { chaiSetup } from '../../src/utils/chai_setup';
-import { constants } from '../../src/utils/constants';
-import { OrderFactory } from '../../src/utils/order_factory';
-import { provider, txDefaults, web3Wrapper } from '../../src/utils/web3_wrapper';
+import { TestLibsContract } from '../../generated_contract_wrappers/test_libs';
+import { addressUtils } from '../utils/address_utils';
+import { artifacts } from '../utils/artifacts';
+import { chaiSetup } from '../utils/chai_setup';
+import { constants } from '../utils/constants';
+import { OrderFactory } from '../utils/order_factory';
+import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
 
 chaiSetup.configure();
 const expect = chai.expect;
diff --git a/packages/contracts/test/exchange/match_orders.ts b/packages/contracts/test/exchange/match_orders.ts
index e23ab9851..0d07d156f 100644
--- a/packages/contracts/test/exchange/match_orders.ts
+++ b/packages/contracts/test/exchange/match_orders.ts
@@ -1,27 +1,27 @@
 import { BlockchainLifecycle } from '@0xproject/dev-utils';
 import { assetProxyUtils } from '@0xproject/order-utils';
-import { AssetProxyId, RevertReason } from '@0xproject/types';
+import { RevertReason } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import * as chai from 'chai';
 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 { 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';
-import { constants } from '../../src/utils/constants';
-import { ERC20Wrapper } from '../../src/utils/erc20_wrapper';
-import { ERC721Wrapper } from '../../src/utils/erc721_wrapper';
-import { ExchangeWrapper } from '../../src/utils/exchange_wrapper';
-import { MatchOrderTester } from '../../src/utils/match_order_tester';
-import { OrderFactory } from '../../src/utils/order_factory';
-import { ERC20BalancesByOwner, ERC721TokenIdsByOwner, OrderInfo, OrderStatus } from '../../src/utils/types';
-import { provider, txDefaults, web3Wrapper } from '../../src/utils/web3_wrapper';
+import { DummyERC20TokenContract } from '../../generated_contract_wrappers/dummy_e_r_c20_token';
+import { DummyERC721TokenContract } from '../../generated_contract_wrappers/dummy_e_r_c721_token';
+import { ERC20ProxyContract } from '../../generated_contract_wrappers/e_r_c20_proxy';
+import { ERC721ProxyContract } from '../../generated_contract_wrappers/e_r_c721_proxy';
+import { ExchangeContract } from '../../generated_contract_wrappers/exchange';
+import { artifacts } from '../utils/artifacts';
+import { expectRevertReasonOrAlwaysFailingTransactionAsync } from '../utils/assertions';
+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 { MatchOrderTester } from '../utils/match_order_tester';
+import { OrderFactory } from '../utils/order_factory';
+import { ERC20BalancesByOwner, ERC721TokenIdsByOwner, OrderInfo, OrderStatus } from '../utils/types';
+import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
 
 chaiSetup.configure();
 const expect = chai.expect;
@@ -103,8 +103,8 @@ describe('matchOrders', () => {
             assetProxyUtils.encodeERC20AssetData(zrxToken.address),
         );
         exchangeWrapper = new ExchangeWrapper(exchange, provider);
-        await exchangeWrapper.registerAssetProxyAsync(AssetProxyId.ERC20, erc20Proxy.address, owner);
-        await exchangeWrapper.registerAssetProxyAsync(AssetProxyId.ERC721, erc721Proxy.address, owner);
+        await exchangeWrapper.registerAssetProxyAsync(erc20Proxy.address, owner);
+        await exchangeWrapper.registerAssetProxyAsync(erc721Proxy.address, owner);
         // Authorize ERC20 and ERC721 trades by exchange
         await web3Wrapper.awaitTransactionSuccessAsync(
             await erc20Proxy.addAuthorizedAddress.sendTransactionAsync(exchange.address, {
@@ -651,13 +651,7 @@ describe('matchOrders', () => {
             });
             // Match orders
             return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                matchOrderTester.matchOrdersAndVerifyBalancesAsync(
-                    signedOrderLeft,
-                    signedOrderRight,
-                    takerAddress,
-                    erc20BalancesByOwner,
-                    erc721TokenIdsByOwner,
-                ),
+                exchangeWrapper.matchOrdersAsync(signedOrderLeft, signedOrderRight, takerAddress),
                 RevertReason.NegativeSpreadRequired,
             );
         });
@@ -680,13 +674,7 @@ describe('matchOrders', () => {
             });
             // Match orders
             return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                matchOrderTester.matchOrdersAndVerifyBalancesAsync(
-                    signedOrderLeft,
-                    signedOrderRight,
-                    takerAddress,
-                    erc20BalancesByOwner,
-                    erc721TokenIdsByOwner,
-                ),
+                exchangeWrapper.matchOrdersAsync(signedOrderLeft, signedOrderRight, takerAddress),
                 // We are assuming assetData fields of the right order are the
                 // reverse of the left order, rather than checking equality. This
                 // saves a bunch of gas, but as a result if the assetData fields are
@@ -715,13 +703,7 @@ describe('matchOrders', () => {
             });
             // Match orders
             return expectRevertReasonOrAlwaysFailingTransactionAsync(
-                matchOrderTester.matchOrdersAndVerifyBalancesAsync(
-                    signedOrderLeft,
-                    signedOrderRight,
-                    takerAddress,
-                    erc20BalancesByOwner,
-                    erc721TokenIdsByOwner,
-                ),
+                exchangeWrapper.matchOrdersAsync(signedOrderLeft, signedOrderRight, takerAddress),
                 RevertReason.InvalidOrderSignature,
             );
         });
diff --git a/packages/contracts/test/exchange/signature_validator.ts b/packages/contracts/test/exchange/signature_validator.ts
index 21cc343b3..1db7dfc6d 100644
--- a/packages/contracts/test/exchange/signature_validator.ts
+++ b/packages/contracts/test/exchange/signature_validator.ts
@@ -8,17 +8,17 @@ import ethUtil = require('ethereumjs-util');
 import {
     SignatureValidatorApprovalContractEventArgs,
     TestSignatureValidatorContract,
-} from '../../src/generated_contract_wrappers/test_signature_validator';
-import { TestValidatorContract } from '../../src/generated_contract_wrappers/test_validator';
-import { TestWalletContract } from '../../src/generated_contract_wrappers/test_wallet';
-import { addressUtils } from '../../src/utils/address_utils';
-import { artifacts } from '../../src/utils/artifacts';
-import { expectRevertOrOtherErrorAsync } from '../../src/utils/assertions';
-import { chaiSetup } from '../../src/utils/chai_setup';
-import { constants } from '../../src/utils/constants';
-import { LogDecoder } from '../../src/utils/log_decoder';
-import { OrderFactory } from '../../src/utils/order_factory';
-import { provider, txDefaults, web3Wrapper } from '../../src/utils/web3_wrapper';
+} from '../../generated_contract_wrappers/test_signature_validator';
+import { TestValidatorContract } from '../../generated_contract_wrappers/test_validator';
+import { TestWalletContract } from '../../generated_contract_wrappers/test_wallet';
+import { addressUtils } from '../utils/address_utils';
+import { artifacts } from '../utils/artifacts';
+import { expectRevertOrOtherErrorAsync } from '../utils/assertions';
+import { chaiSetup } from '../utils/chai_setup';
+import { constants } from '../utils/constants';
+import { LogDecoder } from '../utils/log_decoder';
+import { OrderFactory } from '../utils/order_factory';
+import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
 
 chaiSetup.configure();
 const expect = chai.expect;
diff --git a/packages/contracts/test/exchange/transactions.ts b/packages/contracts/test/exchange/transactions.ts
index c4de58bb9..4f8b49e0e 100644
--- a/packages/contracts/test/exchange/transactions.ts
+++ b/packages/contracts/test/exchange/transactions.ts
@@ -1,26 +1,26 @@
 import { BlockchainLifecycle } from '@0xproject/dev-utils';
 import { assetProxyUtils, generatePseudoRandomSalt } from '@0xproject/order-utils';
-import { AssetProxyId, OrderWithoutExchangeAddress, RevertReason, SignedOrder } from '@0xproject/types';
+import { 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';
-import { ExchangeContract } from '../../src/generated_contract_wrappers/exchange';
-import { ExchangeWrapperContract } from '../../src/generated_contract_wrappers/exchange_wrapper';
-import { WhitelistContract } from '../../src/generated_contract_wrappers/whitelist';
-import { artifacts } from '../../src/utils/artifacts';
-import { expectRevertReasonOrAlwaysFailingTransactionAsync } from '../../src/utils/assertions';
-import { chaiSetup } from '../../src/utils/chai_setup';
-import { constants } from '../../src/utils/constants';
-import { ERC20Wrapper } from '../../src/utils/erc20_wrapper';
-import { ExchangeWrapper } from '../../src/utils/exchange_wrapper';
-import { OrderFactory } from '../../src/utils/order_factory';
-import { orderUtils } from '../../src/utils/order_utils';
-import { TransactionFactory } from '../../src/utils/transaction_factory';
-import { ERC20BalancesByOwner, SignedTransaction } from '../../src/utils/types';
-import { provider, txDefaults, web3Wrapper } from '../../src/utils/web3_wrapper';
+import { DummyERC20TokenContract } from '../../generated_contract_wrappers/dummy_e_r_c20_token';
+import { ERC20ProxyContract } from '../../generated_contract_wrappers/e_r_c20_proxy';
+import { ExchangeContract } from '../../generated_contract_wrappers/exchange';
+import { ExchangeWrapperContract } from '../../generated_contract_wrappers/exchange_wrapper';
+import { WhitelistContract } from '../../generated_contract_wrappers/whitelist';
+import { artifacts } from '../utils/artifacts';
+import { expectRevertReasonOrAlwaysFailingTransactionAsync } from '../utils/assertions';
+import { chaiSetup } from '../utils/chai_setup';
+import { constants } from '../utils/constants';
+import { ERC20Wrapper } from '../utils/erc20_wrapper';
+import { ExchangeWrapper } from '../utils/exchange_wrapper';
+import { OrderFactory } from '../utils/order_factory';
+import { orderUtils } from '../utils/order_utils';
+import { TransactionFactory } from '../utils/transaction_factory';
+import { ERC20BalancesByOwner, SignedTransaction } from '../utils/types';
+import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
 
 chaiSetup.configure();
 const expect = chai.expect;
@@ -91,7 +91,7 @@ describe('Exchange transactions', () => {
             assetProxyUtils.encodeERC20AssetData(zrxToken.address),
         );
         exchangeWrapper = new ExchangeWrapper(exchange, provider);
-        await exchangeWrapper.registerAssetProxyAsync(AssetProxyId.ERC20, erc20Proxy.address, owner);
+        await exchangeWrapper.registerAssetProxyAsync(erc20Proxy.address, owner);
 
         await web3Wrapper.awaitTransactionSuccessAsync(
             await erc20Proxy.addAuthorizedAddress.sendTransactionAsync(exchange.address, { from: owner }),
diff --git a/packages/contracts/test/exchange/wrapper.ts b/packages/contracts/test/exchange/wrapper.ts
index 1af8bde9d..7942f7695 100644
--- a/packages/contracts/test/exchange/wrapper.ts
+++ b/packages/contracts/test/exchange/wrapper.ts
@@ -1,26 +1,26 @@
 import { BlockchainLifecycle } from '@0xproject/dev-utils';
 import { assetProxyUtils } from '@0xproject/order-utils';
-import { AssetProxyId, RevertReason, SignedOrder } from '@0xproject/types';
+import { RevertReason, SignedOrder } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import * as chai from 'chai';
 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 { 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';
-import { constants } from '../../src/utils/constants';
-import { ERC20Wrapper } from '../../src/utils/erc20_wrapper';
-import { ERC721Wrapper } from '../../src/utils/erc721_wrapper';
-import { ExchangeWrapper } from '../../src/utils/exchange_wrapper';
-import { OrderFactory } from '../../src/utils/order_factory';
-import { ERC20BalancesByOwner } from '../../src/utils/types';
-import { provider, txDefaults, web3Wrapper } from '../../src/utils/web3_wrapper';
+import { DummyERC20TokenContract } from '../../generated_contract_wrappers/dummy_e_r_c20_token';
+import { DummyERC721TokenContract } from '../../generated_contract_wrappers/dummy_e_r_c721_token';
+import { ERC20ProxyContract } from '../../generated_contract_wrappers/e_r_c20_proxy';
+import { ERC721ProxyContract } from '../../generated_contract_wrappers/e_r_c721_proxy';
+import { ExchangeContract } from '../../generated_contract_wrappers/exchange';
+import { artifacts } from '../utils/artifacts';
+import { expectRevertReasonOrAlwaysFailingTransactionAsync } from '../utils/assertions';
+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 { OrderFactory } from '../utils/order_factory';
+import { ERC20BalancesByOwner } from '../utils/types';
+import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
 
 chaiSetup.configure();
 const expect = chai.expect;
@@ -87,8 +87,8 @@ describe('Exchange wrappers', () => {
             assetProxyUtils.encodeERC20AssetData(zrxToken.address),
         );
         exchangeWrapper = new ExchangeWrapper(exchange, provider);
-        await exchangeWrapper.registerAssetProxyAsync(AssetProxyId.ERC20, erc20Proxy.address, owner);
-        await exchangeWrapper.registerAssetProxyAsync(AssetProxyId.ERC721, erc721Proxy.address, owner);
+        await exchangeWrapper.registerAssetProxyAsync(erc20Proxy.address, owner);
+        await exchangeWrapper.registerAssetProxyAsync(erc721Proxy.address, owner);
 
         await web3Wrapper.awaitTransactionSuccessAsync(
             await erc20Proxy.addAuthorizedAddress.sendTransactionAsync(exchange.address, {
diff --git a/packages/contracts/test/global_hooks.ts b/packages/contracts/test/global_hooks.ts
index 83263c5b3..cf7c52efd 100644
--- a/packages/contracts/test/global_hooks.ts
+++ b/packages/contracts/test/global_hooks.ts
@@ -1,7 +1,7 @@
 import { env, EnvVars } from '@0xproject/dev-utils';
 
-import { coverage } from '../src/utils/coverage';
-import { profiler } from '../src/utils/profiler';
+import { coverage } from './utils/coverage';
+import { profiler } from './utils/profiler';
 
 after('generate coverage report', async () => {
     if (env.parseBoolean(EnvVars.SolidityCoverage)) {
diff --git a/packages/contracts/test/libraries/lib_bytes.ts b/packages/contracts/test/libraries/lib_bytes.ts
index 3d4058cbc..963b51b8f 100644
--- a/packages/contracts/test/libraries/lib_bytes.ts
+++ b/packages/contracts/test/libraries/lib_bytes.ts
@@ -7,12 +7,12 @@ import * as chai from 'chai';
 import ethUtil = require('ethereumjs-util');
 import * as _ from 'lodash';
 
-import { TestLibBytesContract } from '../../src/generated_contract_wrappers/test_lib_bytes';
-import { artifacts } from '../../src/utils/artifacts';
-import { expectRevertOrOtherErrorAsync } from '../../src/utils/assertions';
-import { chaiSetup } from '../../src/utils/chai_setup';
-import { constants } from '../../src/utils/constants';
-import { provider, txDefaults, web3Wrapper } from '../../src/utils/web3_wrapper';
+import { TestLibBytesContract } from '../../generated_contract_wrappers/test_lib_bytes';
+import { artifacts } from '../utils/artifacts';
+import { expectRevertOrOtherErrorAsync } from '../utils/assertions';
+import { chaiSetup } from '../utils/chai_setup';
+import { constants } from '../utils/constants';
+import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
 
 chaiSetup.configure();
 const expect = chai.expect;
diff --git a/packages/contracts/test/asset_proxy_owner.ts b/packages/contracts/test/multisig/asset_proxy_owner.ts
index 188cba5a3..cde86dd46 100644
--- a/packages/contracts/test/asset_proxy_owner.ts
+++ b/packages/contracts/test/multisig/asset_proxy_owner.ts
@@ -9,19 +9,19 @@ import {
     ExecutionContractEventArgs,
     ExecutionFailureContractEventArgs,
     SubmissionContractEventArgs,
-} from '../src/generated_contract_wrappers/asset_proxy_owner';
-import { MixinAuthorizableContract } from '../src/generated_contract_wrappers/mixin_authorizable';
-import { TestAssetProxyOwnerContract } from '../src/generated_contract_wrappers/test_asset_proxy_owner';
-import { artifacts } from '../src/utils/artifacts';
+} from '../../generated_contract_wrappers/asset_proxy_owner';
+import { MixinAuthorizableContract } from '../../generated_contract_wrappers/mixin_authorizable';
+import { TestAssetProxyOwnerContract } from '../../generated_contract_wrappers/test_asset_proxy_owner';
+import { artifacts } from '../utils/artifacts';
 import {
     expectRevertOrAlwaysFailingTransactionAsync,
     expectRevertOrContractCallFailedAsync,
-} from '../src/utils/assertions';
-import { chaiSetup } from '../src/utils/chai_setup';
-import { constants } from '../src/utils/constants';
-import { increaseTimeAndMineBlockAsync } from '../src/utils/increase_time';
-import { MultiSigWrapper } from '../src/utils/multi_sig_wrapper';
-import { provider, txDefaults, web3Wrapper } from '../src/utils/web3_wrapper';
+} from '../utils/assertions';
+import { chaiSetup } from '../utils/chai_setup';
+import { constants } from '../utils/constants';
+import { increaseTimeAndMineBlockAsync } from '../utils/increase_time';
+import { MultiSigWrapper } from '../utils/multi_sig_wrapper';
+import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
 
 chaiSetup.configure();
 const expect = chai.expect;
diff --git a/packages/contracts/test/multi_sig_with_time_lock.ts b/packages/contracts/test/multisig/multi_sig_with_time_lock.ts
index aa82b9edf..a746403d2 100644
--- a/packages/contracts/test/multi_sig_with_time_lock.ts
+++ b/packages/contracts/test/multisig/multi_sig_with_time_lock.ts
@@ -6,14 +6,14 @@ import { LogWithDecodedArgs } from 'ethereum-types';
 import {
     MultiSigWalletWithTimeLockContract,
     SubmissionContractEventArgs,
-} from '../src/generated_contract_wrappers/multi_sig_wallet_with_time_lock';
-import { artifacts } from '../src/utils/artifacts';
-import { expectRevertOrAlwaysFailingTransactionAsync } from '../src/utils/assertions';
-import { chaiSetup } from '../src/utils/chai_setup';
-import { constants } from '../src/utils/constants';
-import { increaseTimeAndMineBlockAsync } from '../src/utils/increase_time';
-import { MultiSigWrapper } from '../src/utils/multi_sig_wrapper';
-import { provider, txDefaults, web3Wrapper } from '../src/utils/web3_wrapper';
+} from '../../generated_contract_wrappers/multi_sig_wallet_with_time_lock';
+import { artifacts } from '../utils/artifacts';
+import { expectRevertOrAlwaysFailingTransactionAsync } from '../utils/assertions';
+import { chaiSetup } from '../utils/chai_setup';
+import { constants } from '../utils/constants';
+import { increaseTimeAndMineBlockAsync } from '../utils/increase_time';
+import { MultiSigWrapper } from '../utils/multi_sig_wrapper';
+import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
 
 chaiSetup.configure();
 const expect = chai.expect;
diff --git a/packages/contracts/test/token_registry.ts b/packages/contracts/test/token_registry.ts
index 095cecfce..32f8cdee3 100644
--- a/packages/contracts/test/token_registry.ts
+++ b/packages/contracts/test/token_registry.ts
@@ -4,13 +4,14 @@ import * as chai from 'chai';
 import ethUtil = require('ethereumjs-util');
 import * as _ from 'lodash';
 
-import { TokenRegistryContract } from '../src/generated_contract_wrappers/token_registry';
-import { artifacts } from '../src/utils/artifacts';
-import { expectRevertOrAlwaysFailingTransactionAsync } from '../src/utils/assertions';
-import { chaiSetup } from '../src/utils/chai_setup';
-import { constants } from '../src/utils/constants';
-import { TokenRegWrapper } from '../src/utils/token_registry_wrapper';
-import { provider, txDefaults, web3Wrapper } from '../src/utils/web3_wrapper';
+import { TokenRegistryContract } from '../generated_contract_wrappers/token_registry';
+
+import { artifacts } from './utils/artifacts';
+import { expectRevertOrAlwaysFailingTransactionAsync } from './utils/assertions';
+import { chaiSetup } from './utils/chai_setup';
+import { constants } from './utils/constants';
+import { TokenRegWrapper } from './utils/token_registry_wrapper';
+import { provider, txDefaults, web3Wrapper } from './utils/web3_wrapper';
 
 chaiSetup.configure();
 const expect = chai.expect;
diff --git a/packages/contracts/test/ether_token.ts b/packages/contracts/test/tokens/ether_token.ts
index 01093d309..25ef15595 100644
--- a/packages/contracts/test/ether_token.ts
+++ b/packages/contracts/test/tokens/ether_token.ts
@@ -3,12 +3,12 @@ import { BigNumber } from '@0xproject/utils';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import * as chai from 'chai';
 
-import { WETH9Contract } from '../src/generated_contract_wrappers/weth9';
-import { artifacts } from '../src/utils/artifacts';
-import { expectInsufficientFundsAsync, expectRevertOrAlwaysFailingTransactionAsync } from '../src/utils/assertions';
-import { chaiSetup } from '../src/utils/chai_setup';
-import { constants } from '../src/utils/constants';
-import { provider, txDefaults, web3Wrapper } from '../src/utils/web3_wrapper';
+import { WETH9Contract } from '../../generated_contract_wrappers/weth9';
+import { artifacts } from '../utils/artifacts';
+import { expectInsufficientFundsAsync, expectRevertOrAlwaysFailingTransactionAsync } from '../utils/assertions';
+import { chaiSetup } from '../utils/chai_setup';
+import { constants } from '../utils/constants';
+import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
 
 chaiSetup.configure();
 const expect = chai.expect;
diff --git a/packages/contracts/test/unlimited_allowance_token.ts b/packages/contracts/test/tokens/unlimited_allowance_token.ts
index 0eb82b5fe..09a24950c 100644
--- a/packages/contracts/test/unlimited_allowance_token.ts
+++ b/packages/contracts/test/tokens/unlimited_allowance_token.ts
@@ -3,12 +3,12 @@ import { RevertReason } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import * as chai from 'chai';
 
-import { DummyERC20TokenContract } from '../src/generated_contract_wrappers/dummy_e_r_c20_token';
-import { artifacts } from '../src/utils/artifacts';
-import { expectRevertOrOtherErrorAsync } from '../src/utils/assertions';
-import { chaiSetup } from '../src/utils/chai_setup';
-import { constants } from '../src/utils/constants';
-import { provider, txDefaults, web3Wrapper } from '../src/utils/web3_wrapper';
+import { DummyERC20TokenContract } from '../../generated_contract_wrappers/dummy_e_r_c20_token';
+import { artifacts } from '../utils/artifacts';
+import { expectRevertOrOtherErrorAsync } from '../utils/assertions';
+import { chaiSetup } from '../utils/chai_setup';
+import { constants } from '../utils/constants';
+import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
 
 chaiSetup.configure();
 const expect = chai.expect;
diff --git a/packages/contracts/test/zrx_token.ts b/packages/contracts/test/tokens/zrx_token.ts
index 01ae57d4a..a0d77c924 100644
--- a/packages/contracts/test/zrx_token.ts
+++ b/packages/contracts/test/tokens/zrx_token.ts
@@ -3,11 +3,11 @@ import { BigNumber } from '@0xproject/utils';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import * as chai from 'chai';
 
-import { ZRXTokenContract } from '../src/generated_contract_wrappers/zrx_token';
-import { artifacts } from '../src/utils/artifacts';
-import { chaiSetup } from '../src/utils/chai_setup';
-import { constants } from '../src/utils/constants';
-import { provider, txDefaults, web3Wrapper } from '../src/utils/web3_wrapper';
+import { ZRXTokenContract } from '../../generated_contract_wrappers/zrx_token';
+import { artifacts } from '../utils/artifacts';
+import { chaiSetup } from '../utils/chai_setup';
+import { constants } from '../utils/constants';
+import { provider, txDefaults, web3Wrapper } from '../utils/web3_wrapper';
 
 chaiSetup.configure();
 const expect = chai.expect;
diff --git a/packages/contracts/src/abstract/abstract_asset_wrapper.ts b/packages/contracts/test/utils/abstract_asset_wrapper.ts
index 4b56a8502..4b56a8502 100644
--- a/packages/contracts/src/abstract/abstract_asset_wrapper.ts
+++ b/packages/contracts/test/utils/abstract_asset_wrapper.ts
diff --git a/packages/contracts/src/utils/address_utils.ts b/packages/contracts/test/utils/address_utils.ts
index a9fb6921a..a9fb6921a 100644
--- a/packages/contracts/src/utils/address_utils.ts
+++ b/packages/contracts/test/utils/address_utils.ts
diff --git a/packages/contracts/test/utils/artifacts.ts b/packages/contracts/test/utils/artifacts.ts
new file mode 100644
index 000000000..23e93c085
--- /dev/null
+++ b/packages/contracts/test/utils/artifacts.ts
@@ -0,0 +1,51 @@
+import { ContractArtifact } from '@0xproject/sol-compiler';
+
+import * as AssetProxyOwner from '../../artifacts/AssetProxyOwner.json';
+import * as DummyERC20Token from '../../artifacts/DummyERC20Token.json';
+import * as DummyERC721Receiver from '../../artifacts/DummyERC721Receiver.json';
+import * as DummyERC721Token from '../../artifacts/DummyERC721Token.json';
+import * as ERC20Proxy from '../../artifacts/ERC20Proxy.json';
+import * as ERC721Proxy from '../../artifacts/ERC721Proxy.json';
+import * as Exchange from '../../artifacts/Exchange.json';
+import * as ExchangeWrapper from '../../artifacts/ExchangeWrapper.json';
+import * as IAssetProxy from '../../artifacts/IAssetProxy.json';
+import * as MixinAuthorizable from '../../artifacts/MixinAuthorizable.json';
+import * as MultiSigWallet from '../../artifacts/MultiSigWallet.json';
+import * as MultiSigWalletWithTimeLock from '../../artifacts/MultiSigWalletWithTimeLock.json';
+import * as TestAssetProxyDispatcher from '../../artifacts/TestAssetProxyDispatcher.json';
+import * as TestAssetProxyOwner from '../../artifacts/TestAssetProxyOwner.json';
+import * as TestLibBytes from '../../artifacts/TestLibBytes.json';
+import * as TestLibs from '../../artifacts/TestLibs.json';
+import * as TestSignatureValidator from '../../artifacts/TestSignatureValidator.json';
+import * as TestValidator from '../../artifacts/TestValidator.json';
+import * as TestWallet from '../../artifacts/TestWallet.json';
+import * as TokenRegistry from '../../artifacts/TokenRegistry.json';
+import * as EtherToken from '../../artifacts/WETH9.json';
+import * as Whitelist from '../../artifacts/Whitelist.json';
+import * as ZRX from '../../artifacts/ZRXToken.json';
+
+export const artifacts = {
+    AssetProxyOwner: (AssetProxyOwner as any) as ContractArtifact,
+    DummyERC20Token: (DummyERC20Token as any) as ContractArtifact,
+    DummyERC721Receiver: (DummyERC721Receiver as any) as ContractArtifact,
+    DummyERC721Token: (DummyERC721Token as any) as ContractArtifact,
+    ERC20Proxy: (ERC20Proxy as any) as ContractArtifact,
+    ERC721Proxy: (ERC721Proxy as any) as ContractArtifact,
+    Exchange: (Exchange as any) as ContractArtifact,
+    ExchangeWrapper: (ExchangeWrapper as any) as ContractArtifact,
+    EtherToken: (EtherToken as any) as ContractArtifact,
+    IAssetProxy: (IAssetProxy as any) as ContractArtifact,
+    MixinAuthorizable: (MixinAuthorizable as any) as ContractArtifact,
+    MultiSigWallet: (MultiSigWallet as any) as ContractArtifact,
+    MultiSigWalletWithTimeLock: (MultiSigWalletWithTimeLock as any) as ContractArtifact,
+    TestAssetProxyOwner: (TestAssetProxyOwner as any) as ContractArtifact,
+    TestAssetProxyDispatcher: (TestAssetProxyDispatcher as any) as ContractArtifact,
+    TestLibBytes: (TestLibBytes as any) as ContractArtifact,
+    TestLibs: (TestLibs as any) as ContractArtifact,
+    TestSignatureValidator: (TestSignatureValidator as any) as ContractArtifact,
+    TestValidator: (TestValidator as any) as ContractArtifact,
+    TestWallet: (TestWallet as any) as ContractArtifact,
+    TokenRegistry: (TokenRegistry as any) as ContractArtifact,
+    Whitelist: (Whitelist as any) as ContractArtifact,
+    ZRX: (ZRX as any) as ContractArtifact,
+};
diff --git a/packages/contracts/src/utils/assertions.ts b/packages/contracts/test/utils/assertions.ts
index e702a3200..baba892d3 100644
--- a/packages/contracts/src/utils/assertions.ts
+++ b/packages/contracts/test/utils/assertions.ts
@@ -1,8 +1,10 @@
 import { RevertReason } from '@0xproject/types';
 import * as chai from 'chai';
+import { TransactionReceipt, TransactionReceiptWithDecodedLogs } from 'ethereum-types';
 import * as _ from 'lodash';
 
 import { constants } from './constants';
+import { web3Wrapper } from './web3_wrapper';
 
 const expect = chai.expect;
 
@@ -53,18 +55,45 @@ export function expectRevertOrAlwaysFailingTransactionAsync<T>(p: Promise<T>): P
 }
 
 /**
- * Rejects if the given Promise does not reject with the given revert reason or "always
- * failing transaction" error.
+ * Rejects if at least one the following conditions is not met:
+ * 1) The given Promise rejects with the given revert reason.
+ * 2) The given Promise rejects with an error containing "always failing transaction"
+ * 3) The given Promise fulfills with a txReceipt that has a status of 0 or '0', indicating the transaction failed.
+ * 4) The given Promise fulfills with a txHash and corresponding txReceipt has a status of 0 or '0'.
  * @param p the Promise which is expected to reject
  * @param reason a specific revert reason
  * @returns a new Promise which will reject if the conditions are not met and
  * otherwise resolve with no value.
  */
-export function expectRevertReasonOrAlwaysFailingTransactionAsync<T>(
-    p: Promise<T>,
+export async function expectRevertReasonOrAlwaysFailingTransactionAsync(
+    p: Promise<string | TransactionReceiptWithDecodedLogs | TransactionReceipt>,
     reason: RevertReason,
-): PromiseLike<void> {
-    return _expectEitherErrorAsync(p, 'always failing transaction', reason);
+): Promise<void> {
+    return p
+        .then(async result => {
+            let txReceiptStatus: string | 0 | 1 | null;
+            if (typeof result === 'string') {
+                // Result is a txHash. We need to make a web3 call to get the receipt.
+                const txReceipt = await web3Wrapper.awaitTransactionMinedAsync(result);
+                txReceiptStatus = txReceipt.status;
+            } else if ('status' in result) {
+                // Result is a TransactionReceiptWithDecodedLogs or TransactionReceipt
+                // and status is a field of result.
+                txReceiptStatus = result.status;
+            } else {
+                throw new Error('Unexpected result type');
+            }
+            expect(_.toString(txReceiptStatus)).to.equal(
+                '0',
+                'transactionReceipt had a non-zero status, indicating success',
+            );
+        })
+        .catch(err => {
+            expect(err.message).to.satisfy(
+                (msg: string) => _.includes(msg, reason) || _.includes(msg, 'always failing transaction'),
+                `Expected ${reason} or 'always failing transaction' but error message was ${err.message}`,
+            );
+        });
 }
 
 /**
diff --git a/packages/contracts/src/utils/asset_wrapper.ts b/packages/contracts/test/utils/asset_wrapper.ts
index 1a7b2b9ed..f291170a2 100644
--- a/packages/contracts/src/utils/asset_wrapper.ts
+++ b/packages/contracts/test/utils/asset_wrapper.ts
@@ -3,8 +3,7 @@ import { AssetProxyId } from '@0xproject/types';
 import { BigNumber, errorUtils } from '@0xproject/utils';
 import * as _ from 'lodash';
 
-import { AbstractAssetWrapper } from '../abstract/abstract_asset_wrapper';
-
+import { AbstractAssetWrapper } from './abstract_asset_wrapper';
 import { constants } from './constants';
 import { ERC20Wrapper } from './erc20_wrapper';
 import { ERC721Wrapper } from './erc721_wrapper';
diff --git a/packages/contracts/src/utils/chai_setup.ts b/packages/contracts/test/utils/chai_setup.ts
index 1a8733093..1a8733093 100644
--- a/packages/contracts/src/utils/chai_setup.ts
+++ b/packages/contracts/test/utils/chai_setup.ts
diff --git a/packages/contracts/src/utils/constants.ts b/packages/contracts/test/utils/constants.ts
index 2b2bd2425..8e68f376d 100644
--- a/packages/contracts/src/utils/constants.ts
+++ b/packages/contracts/test/utils/constants.ts
@@ -27,6 +27,7 @@ export const constants = {
     MAX_ETHERTOKEN_WITHDRAW_GAS: 43000,
     MAX_TOKEN_TRANSFERFROM_GAS: 80000,
     MAX_TOKEN_APPROVE_GAS: 60000,
+    TRANSFER_FROM_GAS: 150000,
     DUMMY_TOKEN_NAME: '',
     DUMMY_TOKEN_SYMBOL: '',
     DUMMY_TOKEN_DECIMALS: new BigNumber(18),
diff --git a/packages/contracts/src/utils/core_combinatorial_utils.ts b/packages/contracts/test/utils/core_combinatorial_utils.ts
index edcb050c6..86979b4ff 100644
--- a/packages/contracts/src/utils/core_combinatorial_utils.ts
+++ b/packages/contracts/test/utils/core_combinatorial_utils.ts
@@ -14,20 +14,21 @@ 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 { ExchangeContract, FillContractEventArgs } from '../../generated_contract_wrappers/exchange';
+
+import { artifacts } from './artifacts';
+import { expectRevertReasonOrAlwaysFailingTransactionAsync } from './assertions';
+import { AssetWrapper } from './asset_wrapper';
+import { chaiSetup } from './chai_setup';
+import { constants } from './constants';
+import { ERC20Wrapper } from './erc20_wrapper';
+import { ERC721Wrapper } from './erc721_wrapper';
+import { ExchangeWrapper } from './exchange_wrapper';
+import { OrderFactoryFromScenario } from './order_factory_from_scenario';
+import { orderUtils } from './order_utils';
+import { signingUtils } from './signing_utils';
+import { SimpleAssetBalanceAndProxyAllowanceFetcher } from './simple_asset_balance_and_proxy_allowance_fetcher';
+import { SimpleOrderFilledCancelledFetcher } from './simple_order_filled_cancelled_fetcher';
 import {
     AllowanceAmountScenario,
     AssetDataScenario,
@@ -39,7 +40,7 @@ import {
     TakerAssetFillAmountScenario,
     TakerScenario,
     TraderStateScenario,
-} from '../utils/types';
+} from './types';
 
 chaiSetup.configure();
 const expect = chai.expect;
@@ -96,8 +97,8 @@ export async function coreCombinatorialUtilsFactoryAsync(
         zrxAssetData,
     );
     const exchangeWrapper = new ExchangeWrapper(exchangeContract, provider);
-    await exchangeWrapper.registerAssetProxyAsync(AssetProxyId.ERC20, erc20Proxy.address, ownerAddress);
-    await exchangeWrapper.registerAssetProxyAsync(AssetProxyId.ERC721, erc721Proxy.address, ownerAddress);
+    await exchangeWrapper.registerAssetProxyAsync(erc20Proxy.address, ownerAddress);
+    await exchangeWrapper.registerAssetProxyAsync(erc721Proxy.address, ownerAddress);
 
     await web3Wrapper.awaitTransactionSuccessAsync(
         await erc20Proxy.addAuthorizedAddress.sendTransactionAsync(exchangeContract.address, {
diff --git a/packages/contracts/src/utils/coverage.ts b/packages/contracts/test/utils/coverage.ts
index de29a3ecc..de29a3ecc 100644
--- a/packages/contracts/src/utils/coverage.ts
+++ b/packages/contracts/test/utils/coverage.ts
diff --git a/packages/contracts/src/utils/erc20_wrapper.ts b/packages/contracts/test/utils/erc20_wrapper.ts
index 7f00e2061..53e9791bc 100644
--- a/packages/contracts/src/utils/erc20_wrapper.ts
+++ b/packages/contracts/test/utils/erc20_wrapper.ts
@@ -4,8 +4,8 @@ import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import { Provider } from 'ethereum-types';
 import * as _ from 'lodash';
 
-import { DummyERC20TokenContract } from '../generated_contract_wrappers/dummy_e_r_c20_token';
-import { ERC20ProxyContract } from '../generated_contract_wrappers/e_r_c20_proxy';
+import { DummyERC20TokenContract } from '../../generated_contract_wrappers/dummy_e_r_c20_token';
+import { ERC20ProxyContract } from '../../generated_contract_wrappers/e_r_c20_proxy';
 
 import { artifacts } from './artifacts';
 import { constants } from './constants';
diff --git a/packages/contracts/src/utils/erc721_wrapper.ts b/packages/contracts/test/utils/erc721_wrapper.ts
index 309135ae4..6347f56e7 100644
--- a/packages/contracts/src/utils/erc721_wrapper.ts
+++ b/packages/contracts/test/utils/erc721_wrapper.ts
@@ -4,8 +4,8 @@ import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import { Provider } from 'ethereum-types';
 import * as _ from 'lodash';
 
-import { DummyERC721TokenContract } from '../generated_contract_wrappers/dummy_e_r_c721_token';
-import { ERC721ProxyContract } from '../generated_contract_wrappers/e_r_c721_proxy';
+import { DummyERC721TokenContract } from '../../generated_contract_wrappers/dummy_e_r_c721_token';
+import { ERC721ProxyContract } from '../../generated_contract_wrappers/e_r_c721_proxy';
 
 import { artifacts } from './artifacts';
 import { constants } from './constants';
diff --git a/packages/contracts/src/utils/exchange_wrapper.ts b/packages/contracts/test/utils/exchange_wrapper.ts
index ad68c8ff4..155d0eeb0 100644
--- a/packages/contracts/src/utils/exchange_wrapper.ts
+++ b/packages/contracts/test/utils/exchange_wrapper.ts
@@ -1,12 +1,10 @@
-import { AssetProxyId, SignedOrder } from '@0xproject/types';
+import { SignedOrder } from '@0xproject/types';
 import { BigNumber } from '@0xproject/utils';
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import { Provider, TransactionReceiptWithDecodedLogs } from 'ethereum-types';
-import * as _ from 'lodash';
 
-import { ExchangeContract } from '../generated_contract_wrappers/exchange';
+import { ExchangeContract } from '../../generated_contract_wrappers/exchange';
 
-import { constants } from './constants';
 import { formatters } from './formatters';
 import { LogDecoder } from './log_decoder';
 import { orderUtils } from './order_utils';
@@ -192,20 +190,10 @@ export class ExchangeWrapper {
         return tx;
     }
     public async registerAssetProxyAsync(
-        assetProxyId: AssetProxyId,
         assetProxyAddress: string,
         from: string,
-        opts: { oldAssetProxyAddressIfExists?: string } = {},
     ): Promise<TransactionReceiptWithDecodedLogs> {
-        const oldAssetProxyAddress = _.isUndefined(opts.oldAssetProxyAddressIfExists)
-            ? constants.NULL_ADDRESS
-            : opts.oldAssetProxyAddressIfExists;
-        const txHash = await this._exchange.registerAssetProxy.sendTransactionAsync(
-            assetProxyId,
-            assetProxyAddress,
-            oldAssetProxyAddress,
-            { from },
-        );
+        const txHash = await this._exchange.registerAssetProxy.sendTransactionAsync(assetProxyAddress, { from });
         const tx = await this._logDecoder.getTxWithDecodedLogsAsync(txHash);
         return tx;
     }
diff --git a/packages/contracts/src/utils/formatters.ts b/packages/contracts/test/utils/formatters.ts
index 32e4787d6..32e4787d6 100644
--- a/packages/contracts/src/utils/formatters.ts
+++ b/packages/contracts/test/utils/formatters.ts
diff --git a/packages/contracts/src/utils/increase_time.ts b/packages/contracts/test/utils/increase_time.ts
index 4565d8dbc..4565d8dbc 100644
--- a/packages/contracts/src/utils/increase_time.ts
+++ b/packages/contracts/test/utils/increase_time.ts
diff --git a/packages/contracts/src/utils/log_decoder.ts b/packages/contracts/test/utils/log_decoder.ts
index 07127ba79..07127ba79 100644
--- a/packages/contracts/src/utils/log_decoder.ts
+++ b/packages/contracts/test/utils/log_decoder.ts
diff --git a/packages/contracts/src/utils/match_order_tester.ts b/packages/contracts/test/utils/match_order_tester.ts
index fbb1b99db..6145779b0 100644
--- a/packages/contracts/src/utils/match_order_tester.ts
+++ b/packages/contracts/test/utils/match_order_tester.ts
@@ -4,15 +4,11 @@ import { BigNumber } from '@0xproject/utils';
 import * as chai from 'chai';
 import * as _ from 'lodash';
 
-import { chaiSetup } from '../utils/chai_setup';
-import { ERC20Wrapper } from '../utils/erc20_wrapper';
-import { ERC721Wrapper } from '../utils/erc721_wrapper';
-import { ExchangeWrapper } from '../utils/exchange_wrapper';
-import {
-    ERC20BalancesByOwner,
-    ERC721TokenIdsByOwner,
-    TransferAmountsByMatchOrders as TransferAmounts,
-} from '../utils/types';
+import { chaiSetup } from './chai_setup';
+import { ERC20Wrapper } from './erc20_wrapper';
+import { ERC721Wrapper } from './erc721_wrapper';
+import { ExchangeWrapper } from './exchange_wrapper';
+import { ERC20BalancesByOwner, ERC721TokenIdsByOwner, TransferAmountsByMatchOrders as TransferAmounts } from './types';
 
 chaiSetup.configure();
 const expect = chai.expect;
diff --git a/packages/contracts/src/utils/multi_sig_wrapper.ts b/packages/contracts/test/utils/multi_sig_wrapper.ts
index b0d4fa8ab..6e7746dfc 100644
--- a/packages/contracts/src/utils/multi_sig_wrapper.ts
+++ b/packages/contracts/test/utils/multi_sig_wrapper.ts
@@ -3,8 +3,8 @@ import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import { Provider, TransactionReceiptWithDecodedLogs } from 'ethereum-types';
 import * as _ from 'lodash';
 
-import { AssetProxyOwnerContract } from '../generated_contract_wrappers/asset_proxy_owner';
-import { MultiSigWalletContract } from '../generated_contract_wrappers/multi_sig_wallet';
+import { AssetProxyOwnerContract } from '../../generated_contract_wrappers/asset_proxy_owner';
+import { MultiSigWalletContract } from '../../generated_contract_wrappers/multi_sig_wallet';
 
 import { LogDecoder } from './log_decoder';
 
diff --git a/packages/contracts/src/utils/order_factory.ts b/packages/contracts/test/utils/order_factory.ts
index 009dbc396..009dbc396 100644
--- a/packages/contracts/src/utils/order_factory.ts
+++ b/packages/contracts/test/utils/order_factory.ts
diff --git a/packages/contracts/src/utils/order_factory_from_scenario.ts b/packages/contracts/test/utils/order_factory_from_scenario.ts
index b150e59f6..9670c1a59 100644
--- a/packages/contracts/src/utils/order_factory_from_scenario.ts
+++ b/packages/contracts/test/utils/order_factory_from_scenario.ts
@@ -2,7 +2,7 @@ import { assetProxyUtils, generatePseudoRandomSalt } from '@0xproject/order-util
 import { Order } from '@0xproject/types';
 import { BigNumber, errorUtils } from '@0xproject/utils';
 
-import { DummyERC721TokenContract } from '../generated_contract_wrappers/dummy_e_r_c721_token';
+import { DummyERC721TokenContract } from '../../generated_contract_wrappers/dummy_e_r_c721_token';
 
 import { constants } from './constants';
 import {
diff --git a/packages/contracts/src/utils/order_utils.ts b/packages/contracts/test/utils/order_utils.ts
index 019f6e74b..019f6e74b 100644
--- a/packages/contracts/src/utils/order_utils.ts
+++ b/packages/contracts/test/utils/order_utils.ts
diff --git a/packages/contracts/src/utils/profiler.ts b/packages/contracts/test/utils/profiler.ts
index 85ee24f22..85ee24f22 100644
--- a/packages/contracts/src/utils/profiler.ts
+++ b/packages/contracts/test/utils/profiler.ts
diff --git a/packages/contracts/src/utils/revert_trace.ts b/packages/contracts/test/utils/revert_trace.ts
index 0bf8384bc..0bf8384bc 100644
--- a/packages/contracts/src/utils/revert_trace.ts
+++ b/packages/contracts/test/utils/revert_trace.ts
diff --git a/packages/contracts/src/utils/signing_utils.ts b/packages/contracts/test/utils/signing_utils.ts
index 9c711c72c..9c711c72c 100644
--- a/packages/contracts/src/utils/signing_utils.ts
+++ b/packages/contracts/test/utils/signing_utils.ts
diff --git a/packages/contracts/src/utils/simple_asset_balance_and_proxy_allowance_fetcher.ts b/packages/contracts/test/utils/simple_asset_balance_and_proxy_allowance_fetcher.ts
index a295a40c4..a295a40c4 100644
--- a/packages/contracts/src/utils/simple_asset_balance_and_proxy_allowance_fetcher.ts
+++ b/packages/contracts/test/utils/simple_asset_balance_and_proxy_allowance_fetcher.ts
diff --git a/packages/contracts/src/utils/simple_order_filled_cancelled_fetcher.ts b/packages/contracts/test/utils/simple_order_filled_cancelled_fetcher.ts
index 24afe36b7..24afe36b7 100644
--- a/packages/contracts/src/utils/simple_order_filled_cancelled_fetcher.ts
+++ b/packages/contracts/test/utils/simple_order_filled_cancelled_fetcher.ts
diff --git a/packages/contracts/src/utils/token_registry_wrapper.ts b/packages/contracts/test/utils/token_registry_wrapper.ts
index 91895aa59..0abf20e03 100644
--- a/packages/contracts/src/utils/token_registry_wrapper.ts
+++ b/packages/contracts/test/utils/token_registry_wrapper.ts
@@ -1,7 +1,7 @@
 import { Web3Wrapper } from '@0xproject/web3-wrapper';
 import { Provider } from 'ethereum-types';
 
-import { TokenRegistryContract } from '../generated_contract_wrappers/token_registry';
+import { TokenRegistryContract } from '../../generated_contract_wrappers/token_registry';
 
 import { Token } from './types';
 
diff --git a/packages/contracts/src/utils/transaction_factory.ts b/packages/contracts/test/utils/transaction_factory.ts
index 348c0715d..348c0715d 100644
--- a/packages/contracts/src/utils/transaction_factory.ts
+++ b/packages/contracts/test/utils/transaction_factory.ts
diff --git a/packages/contracts/src/utils/types.ts b/packages/contracts/test/utils/types.ts
index b792bb90a..b792bb90a 100644
--- a/packages/contracts/src/utils/types.ts
+++ b/packages/contracts/test/utils/types.ts
diff --git a/packages/contracts/src/utils/web3_wrapper.ts b/packages/contracts/test/utils/web3_wrapper.ts
index c9d83a02d..c9d83a02d 100644
--- a/packages/contracts/src/utils/web3_wrapper.ts
+++ b/packages/contracts/test/utils/web3_wrapper.ts