diff --git a/contracts/staking/contracts/src/interfaces/IZrxVault.sol b/contracts/staking/contracts/src/interfaces/IZrxVault.sol
index 88dfd278cf..5a272d64f5 100644
--- a/contracts/staking/contracts/src/interfaces/IZrxVault.sol
+++ b/contracts/staking/contracts/src/interfaces/IZrxVault.sol
@@ -21,8 +21,87 @@ pragma solidity ^0.5.5;
 
 interface IZrxVault {
 
-    function depositFrom(address owner, uint256 amount) external;
-    function withdrawFrom(address owner, uint256 amount) external;
-    function withdrawAllFrom(address owner) external returns (uint256);
-    function balanceOf(address owner) external view returns (uint256);
+    /// @dev This vault manages Zrx Tokens.
+    /// When a user mints stake, their Zrx Tokens are deposited into this vault.
+    /// Similarly, when they burn stake, their Zrx Tokens are withdrawn from this vault.
+    /// There is a "Catastrophic Failure Mode" that, when invoked, only
+    /// allows withdrawals to be made. Once this vault is in catostrophic
+    /// failure mode, it cannot be returned to normal mode; this prevents
+    /// corruption of related state in the staking contract.
+
+    /// @dev Emitted when Zrx Tokens are deposited into the vault.
+    /// @param sender Address of sender (`msg.sender`).
+    /// @param owner of Zrx Tokens.
+    /// @param amount of Zrx Tokens deposited.
+    event ZrxDepositedIntoVault(
+        address indexed sender,
+        address indexed owner,
+        uint256 amount
+    );
+
+    /// @dev Emitted when Zrx Tokens are withdrawn from the vault.
+    /// @param sender Address of sender (`msg.sender`).
+    /// @param owner of Zrx Tokens.
+    /// @param amount of Zrx Tokens withdrawn.
+    event ZrxWithdrawnFromVault(
+        address indexed sender,
+        address indexed owner,
+        uint256 amount
+    );
+
+    /// @dev Emitted when the ERC20 Proxy is changed.
+    /// @param erc20ProxyAddress Address of the new ERC20 proxy.
+    event Erc20ProxyChanged(
+        address erc20ProxyAddress
+    );
+
+    /// @dev Emitted when the Zrx Asset Data is changed.
+    /// @param zrxAssetData New Zrx Asset Data. 
+    event ZrxAssetDataChanged(
+        bytes zrxAssetData
+    );
+
+    /// @dev Sets the ERC20 proxy.
+    /// Note that only the contract owner can call this.
+    /// Note that this can only be called when *not* in Catostrophic Failure mode.
+    /// @param erc20ProxyAddress Address of the 0x ERC20 Proxy.
+    function setErc20Proxy(address erc20ProxyAddress)
+        external;
+
+    /// @dev Sets the Zrx Asset Data.
+    /// Note that only the contract owner can call this.
+    /// Note that this can only be called when *not* in Catostrophic Failure mode.
+    /// @param _zrxAssetData Zrx asset data for the ERC20 Proxy.
+    function setZrxAssetData(bytes calldata _zrxAssetData)
+        external;
+
+    /// @dev Deposit an `amount` of Zrx Tokens from `owner` into the vault.
+    /// Note that only the Staking contract can call this.
+    /// Note that this can only be called when *not* in Catostrophic Failure mode.
+    /// @param owner of Zrx Tokens.
+    /// @param amount of Zrx Tokens to deposit.
+    function depositFrom(address owner, uint256 amount)
+        external;
+
+    /// @dev Withdraw an `amount` of Zrx Tokens to `owner` from the vault.
+    /// Note that only the Staking contract can call this.
+    /// Note that this can only be called when *not* in Catostrophic Failure mode.
+    /// @param owner of Zrx Tokens.
+    /// @param amount of Zrx Tokens to withdraw.
+    function withdrawFrom(address owner, uint256 amount)
+        external;
+
+    /// @dev Withdraw ALL Zrx Tokens to `owner` from the vault.
+    /// Note that this can only be called when *in* Catostrophic Failure mode.
+    /// @param owner of Zrx Tokens.
+    function withdrawAllFrom(address owner)
+        external
+        returns (uint256);
+
+    /// @dev Returns the balance in Zrx Tokens of the `owner`
+    /// @return Balance in Zrx.
+    function balanceOf(address owner)
+        external
+        view
+        returns (uint256);
 }
diff --git a/contracts/staking/contracts/src/stake/MixinZrxVault.sol b/contracts/staking/contracts/src/stake/MixinZrxVault.sol
index 6757f0b3bf..0083a77263 100644
--- a/contracts/staking/contracts/src/stake/MixinZrxVault.sol
+++ b/contracts/staking/contracts/src/stake/MixinZrxVault.sol
@@ -31,13 +31,20 @@ contract MixinZrxVault is
     MixinOwnable
 {
 
-    function setZrxVault(address _zrxVault)
+    /// @dev This mixin contains logic for managing and interfacing with the Zrx Vault.
+    /// (see vaults/ZrxVault.sol).
+
+    /// @dev Set the Zrx Vault.
+    /// @param zrxVaultAddress Address of the Zrx Vault.
+    function setZrxVault(address zrxVaultAddress)
         external
         onlyOwner
     {
-        zrxVault = IZrxVault(_zrxVault);
+        zrxVault = IZrxVault(zrxVaultAddress);
     }
 
+    /// @dev Return the current Zrx Vault
+    /// @return Zrx Vault
     function getZrxVault()
         public
         view
@@ -46,12 +53,18 @@ contract MixinZrxVault is
         return address(zrxVault);
     }
 
+    /// @dev Deposits Zrx Tokens from the `owner` into the vault.
+    /// @param owner of Zrx Tokens
+    /// @param amount of tokens to deposit.
     function _depositFromOwnerIntoZrxVault(address owner, uint256 amount)
         internal
     {
         zrxVault.depositFrom(owner, amount);
     }
 
+    /// @dev Withdraws Zrx Tokens from to `owner` from the vault.
+    /// @param owner of deposited Zrx Tokens
+    /// @param amount of tokens to withdraw.
     function _withdrawToOwnerFromZrxVault(address owner, uint256 amount)
         internal
     {
diff --git a/contracts/staking/contracts/src/vaults/ZrxVault.sol b/contracts/staking/contracts/src/vaults/ZrxVault.sol
index 5c4ecbd43d..44d49c1dca 100644
--- a/contracts/staking/contracts/src/vaults/ZrxVault.sol
+++ b/contracts/staking/contracts/src/vaults/ZrxVault.sol
@@ -31,48 +31,86 @@ contract ZrxVault is
     MixinVaultCore
 {
 
+    /// @dev This vault manages Zrx Tokens.
+    /// When a user mints stake, their Zrx Tokens are deposited into this vault.
+    /// Similarly, when they burn stake, their Zrx Tokens are withdrawn from this vault.
+    /// There is a "Catastrophic Failure Mode" that, when invoked, only
+    /// allows withdrawals to be made. Once this vault is in catostrophic
+    /// failure mode, it cannot be returned to normal mode; this prevents
+    /// corruption of related state in the staking contract.
+
     using LibSafeMath for uint256;
 
     // mapping from Owner to ZRX balance
     mapping (address => uint256) internal balances;
 
+    // 0x ERC20 Proxy
     IAssetProxy internal erc20Proxy;
 
+    // Zrx Token
     IERC20Token internal zrxToken;
 
+    // Asset data for the ERC20 Proxy
     bytes internal zrxAssetData;
 
+    /// @dev Constructor.
+    /// @param erc20ProxyAddress Address of the 0x ERC20 Proxy.
+    /// @param zrxTokenAddress Address of the Zrx Token.
+    /// @param _zrxAssetData Zrx asset data for the ERC20 Proxy.
     constructor(
-        address _erc20ProxyAddress,
-        address _zrxTokenAddress,
+        address erc20ProxyAddress,
+        address zrxTokenAddress,
         bytes memory _zrxAssetData
     )
         public
     {
-        erc20Proxy = IAssetProxy(_erc20ProxyAddress);
-        zrxToken = IERC20Token(_zrxTokenAddress);
+        erc20Proxy = IAssetProxy(erc20ProxyAddress);
+        zrxToken = IERC20Token(zrxTokenAddress);
         zrxAssetData = _zrxAssetData;
     }
 
-    function setErc20Proxy(address _erc20ProxyAddress)
+    /// @dev Sets the ERC20 proxy.
+    /// Note that only the contract owner can call this.
+    /// Note that this can only be called when *not* in Catostrophic Failure mode.
+    /// @param erc20ProxyAddress Address of the 0x ERC20 Proxy.
+    function setErc20Proxy(address erc20ProxyAddress)
         external
         onlyOwner
+        onlyNotInCatostrophicFailure
     {
-        erc20Proxy = IAssetProxy(_erc20ProxyAddress);
+        erc20Proxy = IAssetProxy(erc20ProxyAddress);
+        emit Erc20ProxyChanged(erc20ProxyAddress);
     }
 
+    /// @dev Sets the Zrx Asset Data.
+    /// Note that only the contract owner can call this.
+    /// Note that this can only be called when *not* in Catostrophic Failure mode.
+    /// @param _zrxAssetData Zrx asset data for the ERC20 Proxy.
     function setZrxAssetData(bytes calldata _zrxAssetData)
         external
         onlyOwner
+        onlyNotInCatostrophicFailure
     {
         zrxAssetData = _zrxAssetData;
+        emit ZrxAssetDataChanged(_zrxAssetData);
     }
 
+    /// @dev Deposit an `amount` of Zrx Tokens from `owner` into the vault.
+    /// Note that only the Staking contract can call this.
+    /// Note that this can only be called when *not* in Catostrophic Failure mode.
+    /// @param owner of Zrx Tokens.
+    /// @param amount of Zrx Tokens to deposit.
     function depositFrom(address owner, uint256 amount)
         external
         onlyStakingContract
         onlyNotInCatostrophicFailure
     {
+        // update balance
+        balances[owner] = balances[owner]._add(amount);
+
+        // notify
+        emit ZrxDepositedIntoVault(msg.sender, owner, amount);
+
         // deposit ZRX from owner
         erc20Proxy.transferFrom(
             zrxAssetData,
@@ -80,11 +118,13 @@ contract ZrxVault is
             address(this),
             amount
         );
-
-        // update balance
-        balances[owner] = balances[owner]._add(amount);
     }
 
+    /// @dev Withdraw an `amount` of Zrx Tokens to `owner` from the vault.
+    /// Note that only the Staking contract can call this.
+    /// Note that this can only be called when *not* in Catostrophic Failure mode.
+    /// @param owner of Zrx Tokens.
+    /// @param amount of Zrx Tokens to withdraw.
     function withdrawFrom(address owner, uint256 amount)
         external
         onlyStakingContract
@@ -93,6 +133,9 @@ contract ZrxVault is
         _withdrawFrom(owner, amount);
     }
 
+    /// @dev Withdraw ALL Zrx Tokens to `owner` from the vault.
+    /// Note that this can only be called when *in* Catostrophic Failure mode.
+    /// @param owner of Zrx Tokens.
     function withdrawAllFrom(address owner)
         external
         onlyInCatostrophicFailure
@@ -106,6 +149,8 @@ contract ZrxVault is
         return totalBalance;
     }
 
+    /// @dev Returns the balance in Zrx Tokens of the `owner`
+    /// @return Balance in Zrx.
     function balanceOf(address owner)
         external
         view
@@ -114,6 +159,9 @@ contract ZrxVault is
         return balances[owner];
     }
 
+    /// @dev Withdraw an `amount` of Zrx Tokens to `owner` from the vault.
+    /// @param owner of Zrx Tokens.
+    /// @param amount of Zrx Tokens to withdraw.
     function _withdrawFrom(address owner, uint256 amount)
         internal
     {
@@ -121,6 +169,9 @@ contract ZrxVault is
         // note that this call will revert if trying to withdraw more
         // than the current balance
         balances[owner] = balances[owner]._sub(amount);
+
+        // notify
+        emit ZrxWithdrawnFromVault(msg.sender, owner, amount);
         
         // withdraw ZRX to owner
         zrxToken.transfer(