diff --git a/contracts/Contribution.sol b/contracts/Contribution.sol
index da4de63..919b37e 100644
--- a/contracts/Contribution.sol
+++ b/contracts/Contribution.sol
@@ -1,34 +1,49 @@
-pragma solidity ^0.4.18;
+pragma solidity ^0.4.19;
 
 import "zeppelin-solidity/contracts/token/ERC721/ERC721Token.sol";
 import './upgradeable/Upgradeable.sol';
 
 // ToDo: only load interfaces
 import './Token.sol';
+import './Contributors.sol';
 
 contract Contribution is Upgradeable, ERC721Token {
 
-  struct Contribution {
+  struct ContributionData {
     address contributor;
     uint amount;
-    bool issued;
-    uint proposalId;
-    string url;
-    uint256 claimAfterBlock;
+    bool claimed;
+    bytes32 hashDigest;
+    uint8 hashFunction;
+    uint8 hashSize;
+    string tokenMetadataURL;
+    uint claimAfterBlock;
     bool exists;
   }
   string internal name_;
   string internal symbol_;
 
-  mapping(uint256 => string) contributionURIs;
-
   mapping(uint256 => address) contributionOwner;
   mapping(address => uint256[]) ownedContributions;
 
-  mapping(uint256 => Contribution) public contributions;
+  mapping(uint256 => ContributionData) public contributions;
   uint256 public contributionsCount;
 
   event ContributionAdded(uint256 id, address indexed contributor, uint256 amount);
+  event ContributionClaimed(uint256 id, address indexed contributor, uint256 amount);
+
+  modifier coreOnly() { 
+    require(contributorsContract().addressIsCore(msg.sender));
+    _;
+  }
+  modifier contributorOnly() { 
+    require(contributorsContract().addressExists(msg.sender));
+    _;
+  }
+  
+  function contributorsContract() view public returns (Contributors) {
+    return Contributors(registry.getProxyFor('Contributors'));
+  }
 
   function tokenContract() view public returns (Token) {
     return Token(registry.getProxyFor('Token'));
@@ -42,11 +57,6 @@ contract Contribution is Upgradeable, ERC721Token {
     return symbol_;
   }
 
-  function contributionURI(uint256 contributionId) public view returns (string) {
-    require(exists(contributionId));
-    return contributions[contributionId].url;
-  }
-
   function ownerOf(uint256 contributionId) public view returns (address) {
     require(exists(contributionId));
     return contributions[contributionId].contributor;
@@ -56,14 +66,36 @@ contract Contribution is Upgradeable, ERC721Token {
     return ownedContributions[contributor].length;
   }
 
-  function add(uint256 amount, uint256 proposalId, address contributor, uint256 blocksToWait, string url) public {
+  function tokenOfOwnerByIndex(address contributor, uint index) public view returns (uint) {
+    return ownedContributions[contributor][index];
+  }
+
+  function tokenMetadata(uint contributionId) public view returns (string) {
+    return contributions[contributionId].tokenMetadataURL;
+  }
+
+  function getContribution(uint contributionId) public view returns (uint256 id, address contributor, uint256 amount, bool claimed, bytes32 hashDigest, uint8 hashFunction, uint8 hashSize, uint claimAfterBlock, bool exists) {
+    id = contributionId;
+    ContributionData storage c = contributions[id];
+    return (
+      id,
+      c.contributor,
+      c.amount, 
+      c.claimed, 
+      c.hashDigest,
+      c.hashFunction,
+      c.hashSize,
+      c.claimAfterBlock,
+      c.exists
+    );
+  }
+
+  function add(uint256 amount, address contributor, uint256 blocksToWait) public coreOnly {
     uint contributionId = contributionsCount + 1;
-    var c = contributions[contributionId];
+    ContributionData storage c = contributions[contributionId];
     c.exists = true;
     c.amount = amount;
-    c.issued = false;
-    c.proposalId = proposalId;
-    c.url = url;
+    c.claimed = false;
     c.contributor = contributor;
     c.claimAfterBlock = block.number + blocksToWait;
 
@@ -71,17 +103,19 @@ contract Contribution is Upgradeable, ERC721Token {
 
     contributionOwner[contributionId] = contributor;
     ownedContributions[contributor].push(contributionId);
-
+  
     ContributionAdded(contributionId, contributor, amount);
   }
 
   function claim(uint256 contributionId) public {
-    var c = contributions[contributionId];
+    ContributionData storage c = contributions[contributionId];
     require(c.exists);
-    require(!c.issued);
+    require(!c.claimed);
     require(block.number > c.claimAfterBlock);
+    c.claimed = true;
     tokenContract().mintFor(c.contributor, c.amount, contributionId);
-    c.issued = true;
+    
+    ContributionClaimed(contributionId, c.contributor, c.amount);
   }
 
   function exists(uint256 contributionId) view public returns (bool) {
diff --git a/contracts/Operator.sol b/contracts/Operator.sol
index fb6ec2e..d4b1542 100644
--- a/contracts/Operator.sol
+++ b/contracts/Operator.sol
@@ -121,12 +121,11 @@ contract Operator is Upgradeable {
   }
 
   function executeProposal(uint proposalId) private {
-
     var p = proposals[proposalId];
     require(!p.executed);
     require(p.votesCount >= p.votesNeeded);
     address recipientAddress = contributorsContract().getContributorAddressById(p.contributorId);
-    contributionContract().add(p.amount, proposalId, recipientAddress,  0, '');
+    contributionContract().add(p.amount, recipientAddress, 0);
     p.executed = true;
     ProposalExecuted(proposalId, p.contributorId, p.amount);
   }
diff --git a/lib/abis/Contribution.json b/lib/abis/Contribution.json
new file mode 100644
index 0000000..64b488c
--- /dev/null
+++ b/lib/abis/Contribution.json
@@ -0,0 +1 @@
+[{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_tokenId","type":"uint256"}],"name":"approve","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"","type":"uint256"}],"name":"contributions","outputs":[{"name":"contributor","type":"address"},{"name":"amount","type":"uint256"},{"name":"claimed","type":"bool"},{"name":"hashDigest","type":"bytes32"},{"name":"hashFunction","type":"uint8"},{"name":"hashSize","type":"uint8"},{"name":"tokenMetadataURL","type":"string"},{"name":"claimAfterBlock","type":"uint256"},{"name":"exists","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"_tokenId","type":"uint256"}],"name":"approvedFor","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"contributionsCount","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"tokensOf","outputs":[{"name":"","type":"uint256[]"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"implementation","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"_proxiedContractName","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_tokenId","type":"uint256"}],"name":"transfer","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_tokenId","type":"uint256"}],"name":"takeOwnership","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"sender","type":"address"}],"name":"initialize","outputs":[],"payable":true,"stateMutability":"payable","type":"function"},{"anonymous":false,"inputs":[{"indexed":false,"name":"id","type":"uint256"},{"indexed":true,"name":"contributor","type":"address"},{"indexed":false,"name":"amount","type":"uint256"}],"name":"ContributionAdded","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"id","type":"uint256"},{"indexed":true,"name":"contributor","type":"address"},{"indexed":false,"name":"amount","type":"uint256"}],"name":"ContributionClaimed","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"_from","type":"address"},{"indexed":true,"name":"_to","type":"address"},{"indexed":false,"name":"_tokenId","type":"uint256"}],"name":"Transfer","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"_owner","type":"address"},{"indexed":true,"name":"_approved","type":"address"},{"indexed":false,"name":"_tokenId","type":"uint256"}],"name":"Approval","type":"event"},{"constant":true,"inputs":[],"name":"contributorsContract","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"tokenContract","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"contributionId","type":"uint256"}],"name":"ownerOf","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"contributor","type":"address"}],"name":"balanceOf","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"contributor","type":"address"},{"name":"index","type":"uint256"}],"name":"tokenOfOwnerByIndex","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"contributionId","type":"uint256"}],"name":"tokenMetadata","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[{"name":"contributionId","type":"uint256"}],"name":"getContribution","outputs":[{"name":"id","type":"uint256"},{"name":"contributor","type":"address"},{"name":"amount","type":"uint256"},{"name":"claimed","type":"bool"},{"name":"hashDigest","type":"bytes32"},{"name":"hashFunction","type":"uint8"},{"name":"hashSize","type":"uint8"},{"name":"claimAfterBlock","type":"uint256"},{"name":"exists","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"amount","type":"uint256"},{"name":"contributor","type":"address"},{"name":"blocksToWait","type":"uint256"}],"name":"add","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"contributionId","type":"uint256"}],"name":"claim","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"contributionId","type":"uint256"}],"name":"exists","outputs":[{"name":"","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"}]
\ No newline at end of file
diff --git a/lib/abis/Operator.json b/lib/abis/Operator.json
index f099710..fe21bd3 100644
--- a/lib/abis/Operator.json
+++ b/lib/abis/Operator.json
@@ -1 +1 @@
-[{"constant":true,"inputs":[{"name":"","type":"uint256"}],"name":"proposals","outputs":[{"name":"creatorAccount","type":"address"},{"name":"contributorId","type":"uint256"},{"name":"votesCount","type":"uint256"},{"name":"votesNeeded","type":"uint256"},{"name":"amount","type":"uint256"},{"name":"executed","type":"bool"},{"name":"ipfsHash","type":"bytes32"},{"name":"hashFunction","type":"uint8"},{"name":"hashSize","type":"uint8"},{"name":"exists","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"proposalsCount","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"implementation","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"_proxiedContractName","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"sender","type":"address"}],"name":"initialize","outputs":[],"payable":true,"stateMutability":"payable","type":"function"},{"anonymous":false,"inputs":[{"indexed":false,"name":"id","type":"uint256"},{"indexed":false,"name":"creatorAccount","type":"address"},{"indexed":false,"name":"contributorId","type":"uint256"},{"indexed":false,"name":"amount","type":"uint256"}],"name":"ProposalCreated","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"id","type":"uint256"},{"indexed":false,"name":"voterId","type":"uint256"},{"indexed":false,"name":"totalVotes","type":"uint256"}],"name":"ProposalVoted","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"id","type":"uint256"},{"indexed":false,"name":"contributorId","type":"uint256"},{"indexed":false,"name":"amount","type":"uint256"}],"name":"ProposalExecuted","type":"event"},{"constant":true,"inputs":[],"name":"contributorsContract","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"tokenContract","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"contributorsCount","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"coreContributorsCount","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"contributorId","type":"uint256"},{"name":"amount","type":"uint256"},{"name":"ipfsHash","type":"bytes32"},{"name":"hashFunction","type":"uint8"},{"name":"hashSize","type":"uint8"}],"name":"addProposal","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"proposalId","type":"uint256"}],"name":"getProposal","outputs":[{"name":"id","type":"uint256"},{"name":"creatorAccount","type":"address"},{"name":"contributorId","type":"uint256"},{"name":"votesCount","type":"uint256"},{"name":"votesNeeded","type":"uint256"},{"name":"amount","type":"uint256"},{"name":"executed","type":"bool"},{"name":"ipfsHash","type":"bytes32"},{"name":"hashFunction","type":"uint8"},{"name":"hashSize","type":"uint8"},{"name":"voterIds","type":"uint256[]"},{"name":"exists","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"proposalId","type":"uint256"}],"name":"vote","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_proposalIds","type":"uint256[]"}],"name":"batchVote","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"}]
\ No newline at end of file
+[{"constant":true,"inputs":[{"name":"","type":"uint256"}],"name":"proposals","outputs":[{"name":"creatorAccount","type":"address"},{"name":"contributorId","type":"uint256"},{"name":"votesCount","type":"uint256"},{"name":"votesNeeded","type":"uint256"},{"name":"amount","type":"uint256"},{"name":"executed","type":"bool"},{"name":"ipfsHash","type":"bytes32"},{"name":"hashFunction","type":"uint8"},{"name":"hashSize","type":"uint8"},{"name":"exists","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"proposalsCount","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"implementation","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"_proxiedContractName","outputs":[{"name":"","type":"string"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"sender","type":"address"}],"name":"initialize","outputs":[],"payable":true,"stateMutability":"payable","type":"function"},{"anonymous":false,"inputs":[{"indexed":false,"name":"id","type":"uint256"},{"indexed":false,"name":"creatorAccount","type":"address"},{"indexed":false,"name":"contributorId","type":"uint256"},{"indexed":false,"name":"amount","type":"uint256"}],"name":"ProposalCreated","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"id","type":"uint256"},{"indexed":false,"name":"voterId","type":"uint256"},{"indexed":false,"name":"totalVotes","type":"uint256"}],"name":"ProposalVoted","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"id","type":"uint256"},{"indexed":false,"name":"contributorId","type":"uint256"},{"indexed":false,"name":"amount","type":"uint256"}],"name":"ProposalExecuted","type":"event"},{"constant":true,"inputs":[],"name":"contributorsContract","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"tokenContract","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"contributionContract","outputs":[{"name":"","type":"address"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"contributorsCount","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"coreContributorsCount","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"contributorId","type":"uint256"},{"name":"amount","type":"uint256"},{"name":"ipfsHash","type":"bytes32"},{"name":"hashFunction","type":"uint8"},{"name":"hashSize","type":"uint8"}],"name":"addProposal","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[{"name":"proposalId","type":"uint256"}],"name":"getProposal","outputs":[{"name":"id","type":"uint256"},{"name":"creatorAccount","type":"address"},{"name":"contributorId","type":"uint256"},{"name":"votesCount","type":"uint256"},{"name":"votesNeeded","type":"uint256"},{"name":"amount","type":"uint256"},{"name":"executed","type":"bool"},{"name":"ipfsHash","type":"bytes32"},{"name":"hashFunction","type":"uint8"},{"name":"hashSize","type":"uint8"},{"name":"voterIds","type":"uint256[]"},{"name":"exists","type":"bool"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"proposalId","type":"uint256"}],"name":"vote","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":false,"inputs":[{"name":"_proposalIds","type":"uint256[]"}],"name":"batchVote","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"}]
\ No newline at end of file
diff --git a/lib/contracts/contribution.js b/lib/contracts/contribution.js
new file mode 100644
index 0000000..c7f933d
--- /dev/null
+++ b/lib/contracts/contribution.js
@@ -0,0 +1,51 @@
+const ethers = require('ethers');
+const RSVP = require('rsvp');
+
+const ContributionSerializer = require('../serializers/contribution');
+const Base = require('./base');
+
+class Contribution extends Base {
+  all() {
+    return this.functions.contributionsCount()
+      .then((count) => {
+        count = count.toNumber();
+        let contributions = [];
+
+        for (let id = 1; id <= count; id++) {
+          contributions.push(this.getById(id));
+        }
+
+        return RSVP.all(contributions);
+      });
+  }
+
+  getById(id) {
+    id = ethers.utils.bigNumberify(id);
+
+    return this.functions.getContribution(id)
+      .then((data) => {
+        return this.ipfs.catAndMerge(data, ContributionSerializer.deserialize);
+      });
+
+  }
+
+  getByContributor(contributor) {
+    return this.functions.balanceOf(contributor)
+      then((balance) => {
+        count = balance.toNumber();
+
+        let contributions = [];
+
+        for (let index = 0; index <= count; index++) {
+          this.functions.tokenOfOwnerByIndex(contributor, index)
+            .then((id) => {
+              contributions.push(this.getById(id));
+            });
+        }
+
+        return RSVP.all(contributions);
+      });
+  }
+}
+
+module.exports = Contribution;
diff --git a/lib/contracts/index.js b/lib/contracts/index.js
index a4a1792..ff3dc15 100644
--- a/lib/contracts/index.js
+++ b/lib/contracts/index.js
@@ -1,5 +1,6 @@
 module.exports = {
   Contributors: require('./contributor'),
+  Contribution: require('./contribution'),
   Operator: require('./operator'),
   Token: require('./token'),
   Registry: require('./registry')
diff --git a/lib/kredits.js b/lib/kredits.js
index 9300179..6d17aca 100644
--- a/lib/kredits.js
+++ b/lib/kredits.js
@@ -5,6 +5,7 @@ const Preflight = require('./utils/preflight');
 
 const ABIS = {
   Contributors: require('./abis/Contributors.json'),
+  Contribution: require('./abis/Contribution.json'),
   Operator: require('./abis/Operator.json'),
   Registry: require('./abis/Registry.json'),
   Token: require('./abis/Token.json')
@@ -76,6 +77,10 @@ class Kredits {
     return this.contractFor('token');
   }
 
+  get Contribution() {
+    return this.contractFor('contribution');
+  }
+
   // Should be private
   contractFor(name) {
     if (this.contracts[name]) {
diff --git a/scripts/build-json.js b/scripts/build-json.js
index db00827..0fb057b 100644
--- a/scripts/build-json.js
+++ b/scripts/build-json.js
@@ -8,6 +8,7 @@ const addressesPath = path.join(libPath, 'addresses');
 
 const files = [
   'Contributors',
+  'Contribution',
   'Operator',
   'Registry',
   'Token'