diff --git a/docs/advanced/plp.rst b/docs/advanced/plp.rst
index 274aa92d1b..4428e37cf7 100644
--- a/docs/advanced/plp.rst
+++ b/docs/advanced/plp.rst
@@ -7,59 +7,80 @@ PLP (Pluggable Liquidity PLP) enables anyone to extend the 0x Protocol with thei
 
 Implementing a Liquidity Provider
 =================================
-The only requirement is that the provider implements the interface in `ILiquidityProviderSandbox <https://github.com/0xProject/protocol/blob/development/contracts/zero-ex/contracts/src/external/ILiquidityProviderSandbox.sol>`_.
+The only requirement is that the provider implements the interface in `ILiquidityProvider <https://github.com/0xProject/protocol/blob/development/contracts/zero-ex/contracts/src/vendor/ILiquidityProvider.sol>`_.
+Note that ``sellEthForToken`` and ``sellTokenForEth`` do not need to be implemented if the liquidity provider does not trade ETH/WETH.
 
 .. code-block:: solidity
 
-    /// @dev Calls `sellTokenForToken` on the given `provider` contract to
-    ///      trigger a trade.
-    /// @param provider The address of the on-chain liquidity provider.
+    /// @dev Trades `inputToken` for `outputToken`. The amount of `inputToken`
+    ///      to sell must be transferred to the contract prior to calling this
+    ///      function to trigger the trade.
     /// @param inputToken The token being sold.
     /// @param outputToken The token being bought.
     /// @param recipient The recipient of the bought tokens.
     /// @param minBuyAmount The minimum acceptable amount of `outputToken` to buy.
-    /// @param auxiliaryData Auxiliary data supplied to the `provider` contract.
-    function executeSellTokenForToken(
-        address provider,
+    /// @param auxiliaryData Arbitrary auxiliary data supplied to the contract.
+    /// @return boughtAmount The amount of `outputToken` bought.
+    function sellTokenForToken(
         address inputToken,
         address outputToken,
         address recipient,
         uint256 minBuyAmount,
         bytes calldata auxiliaryData
     )
-        external;
+        external
+        returns (uint256 boughtAmount);
 
-    /// @dev Calls `sellEthForToken` on the given `provider` contract to
-    ///      trigger a trade.
-    /// @param provider The address of the on-chain liquidity provider.
+    /// @dev Trades ETH for token. ETH must either be attached to this function
+    ///      call or sent to the contract prior to calling this function to
+    ///      trigger the trade.
     /// @param outputToken The token being bought.
     /// @param recipient The recipient of the bought tokens.
     /// @param minBuyAmount The minimum acceptable amount of `outputToken` to buy.
-    /// @param auxiliaryData Auxiliary data supplied to the `provider` contract.
-    function executeSellEthForToken(
-        address provider,
+    /// @param auxiliaryData Arbitrary auxiliary data supplied to the contract.
+    /// @return boughtAmount The amount of `outputToken` bought.
+    function sellEthForToken(
         address outputToken,
         address recipient,
         uint256 minBuyAmount,
         bytes calldata auxiliaryData
     )
-        external;
+        external
+        payable
+        returns (uint256 boughtAmount);
 
-    /// @dev Calls `sellTokenForEth` on the given `provider` contract to
-    ///      trigger a trade.
-    /// @param provider The address of the on-chain liquidity provider.
+    /// @dev Trades token for ETH. The token must be sent to the contract prior
+    ///      to calling this function to trigger the trade.
     /// @param inputToken The token being sold.
     /// @param recipient The recipient of the bought tokens.
     /// @param minBuyAmount The minimum acceptable amount of ETH to buy.
-    /// @param auxiliaryData Auxiliary data supplied to the `provider` contract.
-    function executeSellTokenForEth(
-        address provider,
+    /// @param auxiliaryData Arbitrary auxiliary data supplied to the contract.
+    /// @return boughtAmount The amount of ETH bought.
+    function sellTokenForEth(
         address inputToken,
-        address recipient,
+        address payable recipient,
         uint256 minBuyAmount,
         bytes calldata auxiliaryData
     )
-        external;
+        external
+        returns (uint256 boughtAmount);
+
+    /// @dev Quotes the amount of `outputToken` that would be obtained by
+    ///      selling `sellAmount` of `inputToken`.
+    /// @param inputToken Address of the taker token (what to sell). Use
+    ///        the wETH address if selling ETH.
+    /// @param outputToken Address of the maker token (what to buy). Use
+    ///        the wETH address if buying ETH.
+    /// @param sellAmount Amount of `inputToken` to sell.
+    /// @return outputTokenAmount Amount of `outputToken` that would be obtained.
+    function getSellQuote(
+        address inputToken,
+        address outputToken,
+        uint256 sellAmount
+    )
+        external
+        view
+        returns (uint256 outputTokenAmount);
 
 
 Trading with a Liquidity Provider
@@ -98,4 +119,4 @@ To trade with a liquidity provider use the ``sellToLiquidityProvider`` function.
 
 This function transfers tokens from ``msg.sender`` to the liquidity provider then executes the trade through a sandboxed contract external to the Exchange Proxy. The sandbox then executes the trade through the provider. This function then transfers the output tokens to the ``recipient``.
 
-This function will emit a `LiquidityProviderSwap <../basics/events.html#liquidityproviderswap>`_ event if the trade succeeds. It will revert if the amount of ``outputToken`` returned by the Liquidity Provider is less than ``minBuyAmount``.
\ No newline at end of file
+This function will emit a `LiquidityProviderSwap <../basics/events.html#liquidityproviderswap>`_ event if the trade succeeds. It will revert if the amount of ``outputToken`` returned by the Liquidity Provider is less than ``minBuyAmount``.