diff --git a/package.json b/package.json
index dd46c50ee..e44c89a02 100644
--- a/package.json
+++ b/package.json
@@ -94,7 +94,7 @@
     "scratch-paint": "0.2.0-prerelease.20180222192821",
     "scratch-render": "0.1.0-prerelease.1516837442",
     "scratch-storage": "0.4.0",
-    "scratch-vm": "0.1.0-prerelease.1518812805-prerelease.1518812820",
+    "scratch-vm": "0.1.0-prerelease.1519653784-prerelease.1519653801",
     "selenium-webdriver": "3.6.0",
     "startaudiocontext": "1.2.1",
     "style-loader": "^0.20.0",
diff --git a/src/components/asset-panel/selector.jsx b/src/components/asset-panel/selector.jsx
index 012206517..b69707781 100644
--- a/src/components/asset-panel/selector.jsx
+++ b/src/components/asset-panel/selector.jsx
@@ -13,6 +13,7 @@ const Selector = props => {
         items,
         selectedItemIndex,
         onDeleteClick,
+        onDuplicateClick,
         onItemClick
     } = props;
 
@@ -30,6 +31,7 @@ const Selector = props => {
                         selected={index === selectedItemIndex}
                         onClick={onItemClick}
                         onDeleteButtonClick={onDeleteClick}
+                        onDuplicateButtonClick={onDuplicateClick}
                     />
                 ))}
             </Box>
@@ -58,6 +60,7 @@ Selector.propTypes = {
         name: PropTypes.string.isRequired
     })),
     onDeleteClick: PropTypes.func,
+    onDuplicateClick: PropTypes.func,
     onItemClick: PropTypes.func.isRequired,
     selectedItemIndex: PropTypes.number.isRequired
 };
diff --git a/src/containers/costume-tab.jsx b/src/containers/costume-tab.jsx
index bb48f1b5d..e22baebf2 100644
--- a/src/containers/costume-tab.jsx
+++ b/src/containers/costume-tab.jsx
@@ -51,10 +51,21 @@ class CostumeTab extends React.Component {
         bindAll(this, [
             'handleSelectCostume',
             'handleDeleteCostume',
+            'handleDuplicateCostume',
             'handleNewCostume',
             'handleNewBlankCostume'
         ]);
-        this.state = {selectedCostumeIndex: 0};
+        const {
+            editingTarget,
+            sprites,
+            stage
+        } = props;
+        const target = editingTarget && sprites[editingTarget] ? sprites[editingTarget] : stage;
+        if (target && target.currentCostume) {
+            this.state = {selectedCostumeIndex: target.currentCostume};
+        } else {
+            this.state = {selectedCostumeIndex: 0};
+        }
     }
     componentWillReceiveProps (nextProps) {
         const {
@@ -75,6 +86,11 @@ class CostumeTab extends React.Component {
     handleDeleteCostume (costumeIndex) {
         this.props.vm.deleteCostume(costumeIndex);
     }
+    handleDuplicateCostume (costumeIndex) {
+        this.props.vm.duplicateCostume(costumeIndex).then(() => {
+            this.setState({selectedCostumeIndex: costumeIndex + 1});
+        });
+    }
     handleNewCostume () {
         if (!this.props.vm.editingTarget) return;
         const costumes = this.props.vm.editingTarget.getCostumes() || [];
@@ -145,6 +161,7 @@ class CostumeTab extends React.Component {
                 items={target.costumes || []}
                 selectedItemIndex={this.state.selectedCostumeIndex}
                 onDeleteClick={target.costumes.length > 1 ? this.handleDeleteCostume : null}
+                onDuplicateClick={this.handleDuplicateCostume}
                 onItemClick={this.handleSelectCostume}
             >
                 {target.costumes ?
@@ -186,7 +203,8 @@ CostumeTab.propTypes = {
         id: PropTypes.shape({
             costumes: PropTypes.arrayOf(PropTypes.shape({
                 url: PropTypes.string,
-                name: PropTypes.string.isRequired
+                name: PropTypes.string.isRequired,
+                skinId: PropTypes.number
             }))
         })
     }),
diff --git a/src/containers/sound-editor.jsx b/src/containers/sound-editor.jsx
index 781b2cc5f..bbe032c0b 100644
--- a/src/containers/sound-editor.jsx
+++ b/src/containers/sound-editor.jsx
@@ -1,6 +1,7 @@
 import bindAll from 'lodash.bindall';
 import PropTypes from 'prop-types';
 import React from 'react';
+import WavEncoder from 'wav-encoder';
 
 import {connect} from 'react-redux';
 
@@ -9,6 +10,7 @@ import {computeChunkedRMS} from '../lib/audio/audio-util.js';
 import AudioEffects from '../lib/audio/audio-effects.js';
 import SoundEditorComponent from '../components/sound-editor/sound-editor.jsx';
 import AudioBufferPlayer from '../lib/audio/audio-buffer-player.js';
+import log from '../lib/log.js';
 
 const UNDO_STACK_SIZE = 99;
 
@@ -72,11 +74,25 @@ class SoundEditor extends React.Component {
             }
             this.undoStack.push(this.copyCurrentBuffer());
         }
+        // Encode the new sound into a wav so that it can be stored
+        let wavBuffer = null;
+        try {
+            wavBuffer = WavEncoder.encode.sync({
+                sampleRate: sampleRate,
+                channelData: [samples]
+            });
+        } catch (e) {
+            // This error state is mostly for the mock sounds used during testing.
+            // Any incorrect sound buffer trying to get interpretd as a Wav file
+            // should yield this error.
+            log.error(`Encountered error while trying to encode sound update: ${e}`);
+        }
+
         this.resetState(samples, sampleRate);
         this.props.onUpdateSoundBuffer(
             this.props.soundIndex,
-            this.audioBufferPlayer.buffer
-        );
+            this.audioBufferPlayer.buffer,
+            wavBuffer ? new Uint8Array(wavBuffer) : new Uint8Array());
     }
     handlePlay () {
         this.audioBufferPlayer.play(
diff --git a/src/containers/sound-tab.jsx b/src/containers/sound-tab.jsx
index af95c6b0b..8686ae6f9 100644
--- a/src/containers/sound-tab.jsx
+++ b/src/containers/sound-tab.jsx
@@ -26,6 +26,7 @@ class SoundTab extends React.Component {
         bindAll(this, [
             'handleSelectSound',
             'handleDeleteSound',
+            'handleDuplicateSound',
             'handleNewSound'
         ]);
         this.state = {selectedSoundIndex: 0};
@@ -56,6 +57,12 @@ class SoundTab extends React.Component {
         }
     }
 
+    handleDuplicateSound (soundIndex) {
+        this.props.vm.duplicateSound(soundIndex).then(() => {
+            this.setState({selectedSoundIndex: soundIndex + 1});
+        });
+    }
+
     handleNewSound () {
         if (!this.props.vm.editingTarget) {
             return null;
@@ -116,6 +123,7 @@ class SoundTab extends React.Component {
                 }))}
                 selectedItemIndex={this.state.selectedSoundIndex}
                 onDeleteClick={this.handleDeleteSound}
+                onDuplicateClick={this.handleDuplicateSound}
                 onItemClick={this.handleSelectSound}
             >
                 {sprite.sounds && sprite.sounds[this.state.selectedSoundIndex] ? (
diff --git a/test/helpers/selenium-helper.js b/test/helpers/selenium-helper.js
index c8ead9072..b63ea2bf6 100644
--- a/test/helpers/selenium-helper.js
+++ b/test/helpers/selenium-helper.js
@@ -25,6 +25,7 @@ class SeleniumHelper {
         // List of useful xpath scopes for finding elements
         return {
             blocksTab: "*[@id='react-tabs-1']",
+            costumesTab: "*[@id='react-tabs-3']",
             modal: '*[@class="ReactModalPortal"]',
             reportedValue: '*[@class="blocklyDropDownContent"]',
             soundsTab: "*[@id='react-tabs-5']",
diff --git a/test/integration/costumes.test.js b/test/integration/costumes.test.js
index 98f31629a..f07c3d0f3 100644
--- a/test/integration/costumes.test.js
+++ b/test/integration/costumes.test.js
@@ -7,7 +7,9 @@ const {
     findByXpath,
     getDriver,
     getLogs,
-    loadUri
+    loadUri,
+    rightClickText,
+    scope
 } = new SeleniumHelper();
 
 const uri = path.resolve(__dirname, '../../build/index.html');
@@ -36,6 +38,22 @@ describe('Working with costumes', () => {
         await expect(logs).toEqual([]);
     });
 
+    test('Duplicating a costume', async () => {
+        await loadUri(uri);
+        await clickXpath('//button[@title="tryit"]');
+        await clickText('Costumes');
+
+        await rightClickText('costume1', scope.costumesTab);
+        await clickText('duplicate', scope.costumesTab);
+        await new Promise(resolve => setTimeout(resolve, 1000)); // Wait for duplication to finish
+
+        // Make sure the duplicated costume is named correctly.
+        await clickText('costume3', scope.costumesTab);
+
+        const logs = await getLogs();
+        await expect(logs).toEqual([]);
+    });
+
     test('Adding a backdrop', async () => {
         await loadUri(uri);
         await clickXpath('//button[@title="tryit"]');
diff --git a/test/integration/sounds.test.js b/test/integration/sounds.test.js
index 244ebb9b4..e31548684 100644
--- a/test/integration/sounds.test.js
+++ b/test/integration/sounds.test.js
@@ -63,6 +63,22 @@ describe('Working with sounds', () => {
         await expect(logs).toEqual([]);
     });
 
+    test('Duplicating a sound', async () => {
+        await loadUri(uri);
+        await clickXpath('//button[@title="tryit"]');
+        await clickText('Sounds');
+
+        await rightClickText('Meow', scope.soundsTab);
+        await clickText('duplicate', scope.soundsTab);
+        await new Promise(resolve => setTimeout(resolve, 1000)); // Wait for error
+
+        // Make sure the duplicated sound is named correctly.
+        await clickText('Meow2', scope.soundsTab);
+
+        const logs = await getLogs();
+        await expect(logs).toEqual([]);
+    });
+
     // Regression test for gui issue #1320
     test('Switching sprites with different numbers of sounds', async () => {
         await loadUri(uri);