diff --git a/contracts/Project.sol b/contracts/Project.sol
index 9fda19a..01c0af6 100644
--- a/contracts/Project.sol
+++ b/contracts/Project.sol
@@ -2,31 +2,48 @@ pragma solidity ^0.4.2;
 
 contract Project {
 
-  /* public properties */
+  /* Public properties */
   address public owner;
   uint public target;
+  uint public deadline;
   uint public totalAmountRaised;
   address[] public contributors;
   mapping (address => uint) public contributions;
 
-  /* events */
+  /* Internal properties */
+  mapping (address => uint) internal balances;
+  bool hasOwnerWithdrawnFunds = false;
+
+  /* Events */
   event ContributionMade(address contributor, uint amount);
+  event GoalReached(uint amount, address beneficiary);
 
-  function Project(address _owner, uint _target) public {
+  /* Constructor */
+  function Project(address _owner, uint _target, uint _durationInHours) public {
     owner = _owner;
     target = _target;
+    deadline = now + _durationInHours * 1 hours;
   }
 
-  function contribute(address _contributor, uint _amount) public returns (bool success) {
+  /* Modifiers */
+  modifier afterDeadline() { if (now >= deadline) _; }
+  modifier projectOpen() { if (deadline < now) _; }
+
+  /* Publicly-exposed interface */
+
+  function contribute(address _contributor, uint _amount) public projectOpen returns (bool success) {
+    require(_amount > 0);
+
     contributions[_contributor] += _amount;
     totalAmountRaised += _amount;
+    balances[_contributor] += _amount;
     contributors.push(_contributor);
     ContributionMade(_contributor, _amount);
     return true;
   }
 
   function balanceOf(address _contributor) public view returns (uint balance) {
-    return contributions[_contributor];
+    return balances[_contributor];
   }
 
   function isFullyFunded() public view returns (bool funded) {
@@ -37,4 +54,28 @@ contract Project {
     return contributors.length;
   }
 
+  function withdraw() public afterDeadline {
+    if (isFullyFunded()) {
+      withdrawForOwner();
+    } else {
+      withdrawForContributor();
+    }
+  }
+
+  /* Internal functions */
+
+  function withdrawForContributor() internal {
+    if (balances[msg.sender] > 0) {
+      msg.sender.transfer(balances[msg.sender]);
+      balances[msg.sender] = 0;
+    }
+  }
+
+  function withdrawForOwner() internal {
+    if (!hasOwnerWithdrawnFunds) {
+      owner.transfer(totalAmountRaised);
+      hasOwnerWithdrawnFunds = true;
+    }
+  }
+
 }
diff --git a/test/Project.js b/test/Project.js
index 26c1d03..17ecd37 100644
--- a/test/Project.js
+++ b/test/Project.js
@@ -53,4 +53,20 @@ contract("Project", accounts => {
     const numberOfContributions = await contract.numberOfContributions();
     assert.equal(numberOfContributions, 3, "There are 3 contributions.");
   });
+
+  it("should indicate whether a project is open or closed to contribution", async () => {});
+
+  it("should not allow an owner to withdraw funds if project is still open", async () => {});
+
+  it("should allow an owner to withdraw funds if project is closed and successful", async () => {});
+
+  it("should not allow an owner to withdraw funds if project is closed and unsuccessful", async () => {});
+
+  it("should allow a contributor to withdraw funds if project is closed and unsuccessful", async () => {});
+
+  it("should not allow a contributor to withdraw funds if project is closed and successful", async () => {});
+
+  xit("should not allow a contributor to withdraw funds if project is still open", async () => {});
+
+  it("should only allow contributors or owners to withdraw funds", async () => {});
 });