diff --git a/src/extension-support/extension-manager.js b/src/extension-support/extension-manager.js
index 147d57305..cff9f4f0e 100644
--- a/src/extension-support/extension-manager.js
+++ b/src/extension-support/extension-manager.js
@@ -11,6 +11,7 @@ const Scratch3PenBlocks = require('../extensions/scratch3_pen');
 const Scratch3WeDo2Blocks = require('../extensions/scratch3_wedo2');
 const Scratch3MusicBlocks = require('../extensions/scratch3_music');
 const Scratch3MicroBitBlocks = require('../extensions/scratch3_microbit');
+const Scratch3SpeakBlocks = require('../extensions/scratch3_speak');
 const Scratch3TranslateBlocks = require('../extensions/scratch3_translate');
 const Scratch3VideoSensingBlocks = require('../extensions/scratch3_video_sensing');
 const Scratch3SpeechBlocks = require('../extensions/scratch3_speech');
@@ -20,6 +21,7 @@ const builtinExtensions = {
     wedo2: Scratch3WeDo2Blocks,
     music: Scratch3MusicBlocks,
     microbit: Scratch3MicroBitBlocks,
+    speak: Scratch3SpeakBlocks,
     translate: Scratch3TranslateBlocks,
     videoSensing: Scratch3VideoSensingBlocks,
     speech: Scratch3SpeechBlocks
diff --git a/src/extensions/scratch3_speak/index.js b/src/extensions/scratch3_speak/index.js
new file mode 100644
index 000000000..9a64228ff
--- /dev/null
+++ b/src/extensions/scratch3_speak/index.js
@@ -0,0 +1,152 @@
+const formatMessage = require('format-message');
+const nets = require('nets');
+
+const ArgumentType = require('../../extension-support/argument-type');
+const BlockType = require('../../extension-support/block-type');
+const Cast = require('../../util/cast');
+const log = require('../../util/log');
+
+/**
+ * The url of the synthesis server.
+ * @type {string}
+ */
+const SERVER_HOST = 'https://synthesis-service.scratch.mit.edu';
+
+/**
+ * How long to wait in ms before timing out requests to synthesis server.
+ * @type {int}
+ */
+const SERVER_TIMEOUT = 10000; // 10 seconds (chosen arbitrarily).
+
+/**
+ * Class for the synthesis block in Scratch 3.0.
+ * @constructor
+ */
+class Scratch3SpeakBlocks {
+    constructor () {
+        /**
+         * Locale code of the viewer
+         * @type {string}
+         * @private
+         */
+        this._language = this.getViewerLanguageCode();
+    }
+
+    /**
+     * The key to load & store a target's synthesis state.
+     * @return {string} The key.
+     */
+    static get STATE_KEY () {
+        return 'Scratch.speak';
+    }
+
+    /**
+     * @returns {object} metadata for this extension and its blocks.
+     */
+    getInfo () {
+        return {
+            id: 'speak',
+            name: 'Amazon Polly',
+            menuIconURI: '', // @todo Add the final icons.
+            blockIconURI: '',
+            blocks: [
+                {
+                    opcode: 'speakAndWait',
+                    text: formatMessage({
+                        id: 'speak.speakAndWaitBlock',
+                        default: 'speak [WORDS]',
+                        description: 'speak some words'
+                    }),
+                    blockType: BlockType.COMMAND,
+                    arguments: {
+                        WORDS: {
+                            type: ArgumentType.STRING,
+                            defaultValue: formatMessage({
+                                id: 'speak.defaultTextToSpeak',
+                                default: 'hello',
+                                description: 'hello: the default text to speak'
+                            })
+                        }
+                    }
+                }
+            ],
+            menus: {
+                voices: this.supportedVoices
+            }
+        };
+    }
+
+    /**
+     * Get the viewer's language code.
+     * @return {string} the language code.
+     */
+    getViewerLanguageCode () {
+        // @todo This should be the language code of the project *creator*
+        // rather than the project viewer.
+        return navigator.language || navigator.userLanguage || 'en-US';
+    }
+
+    /**
+     * Return the supported voices for the extension.
+     * @return {Array} Supported voices
+     */
+    supportedVoices () {
+        return [
+            'Quinn',
+            'Max',
+            'Squeak',
+            'Monster',
+            'Puppy'
+        ];
+    }
+
+    /**
+     * Convert the provided text into a sound file and then play the file.
+     * @param  {object} args Block arguments
+     * @return {Promise}     A promise that resolves after playing the sound
+     */
+    speakAndWait (args) {
+        // Cast input to string
+        args.WORDS = Cast.toString(args.WORDS);
+
+        // Build up URL
+        let path = `${SERVER_HOST}/synth`;
+        path += `?locale=${this._language}`;
+        path += `&gender=male`; // @todo
+        path += `&text=${encodeURI(args.WORDS)}`;
+
+        // Perform HTTP request to get audio file
+        return new Promise(resolve => {
+            nets({
+                url: path,
+                timeout: SERVER_TIMEOUT
+            }, (err, res, body) => {
+                if (err) {
+                    log.warn(err);
+                    return resolve();
+                }
+
+                if (res.statusCode !== 200) {
+                    log.warn(res.statusCode);
+                    return resolve();
+                }
+
+                // Play the sound
+                const ctx = new (window.AudioContext || window.webkitAudioContext)();
+                const source = ctx.createBufferSource();
+                ctx.decodeAudioData(body.buffer, buffer => {
+                    source.buffer = buffer;
+                    source.connect(ctx.destination);
+                    source.loop = false;
+                }, e => {
+                    log.warn(e.err);
+                });
+                source.addEventListener('ended', () => {
+                    resolve();
+                });
+                source.start(0);
+            });
+        });
+    }
+}
+module.exports = Scratch3SpeakBlocks;