diff --git a/client/constants.js b/client/constants.js
index b69e22b2..1a4f1741 100644
--- a/client/constants.js
+++ b/client/constants.js
@@ -23,5 +23,7 @@ export const NEW_PROJECT = 'NEW_PROJECT';
 export const SET_PROJECT = 'SET_PROJECT';
 export const SET_PROJECTS = 'SET_PROJECTS';
 
+export const SET_SELECTED_FILE = 'SET_SELECTED_FILE';
+
 // eventually, handle errors more specifically and better
 export const ERROR = 'ERROR';
diff --git a/client/modules/IDE/actions/project.js b/client/modules/IDE/actions/project.js
index 8d4e1e56..8f820c30 100644
--- a/client/modules/IDE/actions/project.js
+++ b/client/modules/IDE/actions/project.js
@@ -12,7 +12,8 @@ export function getProject(id) {
         dispatch({
           type: ActionTypes.SET_PROJECT,
           project: response.data,
-          files: response.data.files
+          files: response.data.files,
+          selectedFile: response.data.selectedFile
         });
       })
       .catch(response => dispatch({
@@ -34,7 +35,7 @@ export function saveProject() {
   return (dispatch, getState) => {
     const state = getState();
     const formParams = Object.assign({}, state.project);
-    formParams.files = state.files;
+    formParams.files = [...state.files];
     if (state.project.id) {
       axios.put(`${ROOT_URL}/projects/${state.project.id}`, formParams, { withCredentials: true })
         .then(() => {
@@ -47,6 +48,12 @@ export function saveProject() {
           error: response.data
         }));
     } else {
+      // this might be unnecessary, but to prevent collisions in mongodb
+      formParams.files.map(file => {
+        const newFile = Object.assign({}, file);
+        delete newFile.id;
+        return newFile;
+      });
       axios.post(`${ROOT_URL}/projects`, formParams, { withCredentials: true })
         .then(response => {
           browserHistory.push(`/projects/${response.data.id}`);
@@ -54,6 +61,7 @@ export function saveProject() {
             type: ActionTypes.NEW_PROJECT,
             name: response.data.name,
             id: response.data.id,
+            selectedFile: response.data.selectedFile,
             files: response.data.files
           });
         })
@@ -75,6 +83,7 @@ export function createProject() {
           type: ActionTypes.NEW_PROJECT,
           name: response.data.name,
           id: response.data.id,
+          selectedFile: response.data.selectedFile,
           files: response.data.files
         });
       })
diff --git a/client/modules/IDE/components/Sidebar.js b/client/modules/IDE/components/Sidebar.js
index 3c5d0fe6..4fe0b85b 100644
--- a/client/modules/IDE/components/Sidebar.js
+++ b/client/modules/IDE/components/Sidebar.js
@@ -1,22 +1,32 @@
 import React, { PropTypes } from 'react';
+import classNames from 'classnames';
 
 function Sidebar(props) {
   return (
     <section className="sidebar">
       <ul className="sidebar__file-list">
-        {props.files.map(file =>
-          <li
-            className="sidebar__file-item"
-            key={file.id}
-          >{file.name}</li>
-        )}
+        {props.files.map(file => {
+          let itemClass = classNames({
+            'sidebar__file-item': true,
+            'sidebar__file-item--selected': file.id === props.selectedFile.id
+          });
+          return (
+            <li
+              className={itemClass}
+              key={file.id}
+            >{file.name}</li>
+          );
+        })}
       </ul>
     </section>
   );
 }
 
 Sidebar.propTypes = {
-  files: PropTypes.array.isRequired
+  files: PropTypes.array.isRequired,
+  selectedFile: PropTypes.shape({
+    id: PropTypes.string.isRequired
+  })
 };
 
 export default Sidebar;
diff --git a/client/modules/IDE/pages/IDEView.js b/client/modules/IDE/pages/IDEView.js
index 2278a095..6d891791 100644
--- a/client/modules/IDE/pages/IDEView.js
+++ b/client/modules/IDE/pages/IDEView.js
@@ -11,6 +11,7 @@ import * as FileActions from '../actions/files';
 import * as IDEActions from '../actions/ide';
 import * as PreferencesActions from '../actions/preferences';
 import * as ProjectActions from '../actions/project';
+import { getFile } from '../reducers/files';
 
 class IDEView extends React.Component {
   componentDidMount() {
@@ -45,14 +46,18 @@ class IDEView extends React.Component {
           decreaseFont={this.props.decreaseFont}
           fontSize={this.props.preferences.fontSize}
         />
-        <Sidebar files={this.props.files} />
+        <Sidebar
+          files={this.props.files}
+          selectedFile={this.props.selectedFile}
+        />
         <Editor
-          content={this.props.files[0].content}
+          content={this.props.selectedFile.content}
           updateFileContent={this.props.updateFileContent}
           fontSize={this.props.preferences.fontSize}
+          files={this.props.files}
         />
         <PreviewFrame
-          content={this.props.files[0].content}
+          content={this.props.selectedFile.content}
           head={
             <link type="text/css" rel="stylesheet" href="/preview-styles.css" />
           }
@@ -89,12 +94,17 @@ IDEView.propTypes = {
   increaseFont: PropTypes.func.isRequired,
   decreaseFont: PropTypes.func.isRequired,
   files: PropTypes.array.isRequired,
-  updateFileContent: PropTypes.func.isRequired
+  updateFileContent: PropTypes.func.isRequired,
+  selectedFile: PropTypes.shape({
+    id: PropTypes.string,
+    content: PropTypes.string.isRequired
+  })
 };
 
 function mapStateToProps(state) {
   return {
     files: state.files,
+    selectedFile: getFile(state.files, state.ide.selectedFile),
     ide: state.ide,
     preferences: state.preferences,
     user: state.user,
diff --git a/client/modules/IDE/reducers/files.js b/client/modules/IDE/reducers/files.js
index 3a1a03d5..a8bb6991 100644
--- a/client/modules/IDE/reducers/files.js
+++ b/client/modules/IDE/reducers/files.js
@@ -20,14 +20,18 @@ const defaultHTML =
 </html>
 `;
 
+
+// if the project has never been saved,
 const initialState = [
   {
     name: 'sketch.js',
-    content: defaultSketch
+    content: defaultSketch,
+    id: '1'
   },
   {
     name: 'index.html',
-    content: defaultHTML
+    content: defaultHTML,
+    id: '2'
   }];
 
 
@@ -50,4 +54,6 @@ const files = (state = initialState, action) => {
   }
 };
 
+export const getFile = (state, id) => state.filter(file => file.id === id)[0];
+
 export default files;
diff --git a/client/modules/IDE/reducers/ide.js b/client/modules/IDE/reducers/ide.js
index e89ffdee..5d80ca81 100644
--- a/client/modules/IDE/reducers/ide.js
+++ b/client/modules/IDE/reducers/ide.js
@@ -1,7 +1,8 @@
 import * as ActionTypes from '../../../constants';
 
 const initialState = {
-  isPlaying: false
+  isPlaying: false,
+  selectedFile: '1'
 };
 
 const ide = (state = initialState, action) => {
@@ -18,6 +19,10 @@ const ide = (state = initialState, action) => {
       return {
         isPlaying: false
       };
+    case ActionTypes.SET_SELECTED_FILE:
+    case ActionTypes.SET_PROJECT:
+    case ActionTypes.NEW_PROJECT:
+      return Object.assign({}, state, { selectedFile: action.selectedFile });
     default:
       return state;
   }
diff --git a/package.json b/package.json
index 53f5d57d..6d64719d 100644
--- a/package.json
+++ b/package.json
@@ -60,6 +60,7 @@
     "babel-core": "^6.8.0",
     "bcrypt-nodejs": "0.0.3",
     "body-parser": "^1.15.1",
+    "bson-objectid": "^1.1.4",
     "classnames": "^2.2.5",
     "codemirror": "^5.14.2",
     "connect-mongo": "^1.2.0",
diff --git a/server/controllers/project.controller.js b/server/controllers/project.controller.js
index 03baa4e5..6c8f55c4 100644
--- a/server/controllers/project.controller.js
+++ b/server/controllers/project.controller.js
@@ -2,8 +2,7 @@ import Project from '../models/project';
 
 export function createProject(req, res) {
   const projectValues = {
-    user: req.user ? req.user._id : undefined, // eslint-disable-line no-underscore-dangle
-    file: {}
+    user: req.user ? req.user._id : undefined // eslint-disable-line no-underscore-dangle
   };
 
   Object.assign(projectValues, req.body);
diff --git a/server/models/project.js b/server/models/project.js
index 709ea58d..b000843d 100644
--- a/server/models/project.js
+++ b/server/models/project.js
@@ -40,7 +40,8 @@ const projectSchema = new Schema({
   name: { type: String, default: "Hello p5.js, it's the server" },
   user: { type: Schema.Types.ObjectId, ref: 'User' },
   files: {type: [ fileSchema ], default: [{ name: 'sketch.js', content: defaultSketch, _id: new ObjectId() }, { name: 'index.html', content: defaultHTML, _id: new ObjectId() }]},
-  _id: { type: String, default: shortid.generate }
+  _id: { type: String, default: shortid.generate },
+  selectedFile: Schema.Types.ObjectId
 }, { timestamps: true });
 
 projectSchema.virtual('id').get(function(){
@@ -51,4 +52,12 @@ projectSchema.set('toJSON', {
     virtuals: true
 });
 
+projectSchema.pre('save', function createSelectedFile(next) {
+  const project = this;
+  if (!project.selectedFile) {
+    project.selectedFile = project.files[0]._id; // eslint-disable-line no-underscore-dangle
+    return next();
+  }
+});
+
 export default mongoose.model('Project', projectSchema);