diff --git a/src/blocks/scratch3_wedo2.js b/src/blocks/scratch3_wedo2.js
new file mode 100644
index 00000000..d79ef909
--- /dev/null
+++ b/src/blocks/scratch3_wedo2.js
@@ -0,0 +1,700 @@
+const color = require('../util/color');
+const log = require('../util/log');
+
+/**
+ * Manage power, direction, and timers for one WeDo 2.0 motor.
+ */
+class WeDo2Motor {
+    /**
+     * Construct a WeDo2Motor instance.
+     * @param {WeDo2} parent - the WeDo 2.0 device which owns this motor.
+     * @param {int} index - the zero-based index of this motor on its parent device.
+     */
+    constructor (parent, index) {
+        /**
+         * The WeDo 2.0 device which owns this motor.
+         * @type {WeDo2}
+         * @private
+         */
+        this._parent = parent;
+
+        /**
+         * The zero-based index of this motor on its parent device.
+         * @type {int}
+         * @private
+         */
+        this._index = index;
+
+        /**
+         * This motor's current direction: 1 for "this way" or -1 for "that way"
+         * @type {number}
+         * @private
+         */
+        this._direction = 1;
+
+        /**
+         * This motor's current power level, in the range [0,100].
+         * @type {number}
+         * @private
+         */
+        this._power = 100;
+
+        /**
+         * Is this motor currently moving?
+         * @type {boolean}
+         * @private
+         */
+        this._isOn = false;
+
+        /**
+         * If the motor has been turned on or is actively braking for a specific duration, this is the timeout ID for
+         * the end-of-action handler. Cancel this when changing plans.
+         * @type {Object}
+         * @private
+         */
+        this._pendingTimeoutId = null;
+
+        this.startBraking = this.startBraking.bind(this);
+        this.setMotorOff = this.setMotorOff.bind(this);
+    }
+
+    /**
+     * @return {number} - the duration of active braking after a call to startBraking(). Afterward, turn the motor off.
+     * @constructor
+     */
+    static get BRAKE_TIME_MS () {
+        return 1000;
+    }
+
+    /**
+     * @return {int} - this motor's current direction: 1 for "this way" or -1 for "that way"
+     */
+    get direction () {
+        return this._direction;
+    }
+
+    /**
+     * @param {int} value - this motor's new direction: 1 for "this way" or -1 for "that way"
+     */
+    set direction (value) {
+        if (value < 0) {
+            this._direction = -1;
+        } else {
+            this._direction = 1;
+        }
+    }
+
+    /**
+     * @return {int} - this motor's current power level, in the range [0,100].
+     */
+    get power () {
+        return this._power;
+    }
+
+    /**
+     * @param {int} value - this motor's new power level, in the range [0,100].
+     */
+    set power (value) {
+        this._power = Math.max(0, Math.min(value, 100));
+    }
+
+    /**
+     * @return {boolean} - true if this motor is currently moving, false if this motor is off or braking.
+     */
+    get isOn () {
+        return this._isOn;
+    }
+
+    /**
+     * Turn this motor on indefinitely.
+     */
+    setMotorOn () {
+        this._parent._send('motorOn', {motorIndex: this._index, power: this._direction * this._power});
+        this._isOn = true;
+        this._clearTimeout();
+    }
+
+    /**
+     * Turn this motor on for a specific duration.
+     * @param {number} milliseconds - run the motor for this long.
+     */
+    setMotorOnFor (milliseconds) {
+        milliseconds = Math.max(0, milliseconds);
+        this.setMotorOn();
+        this._setNewTimeout(this.startBraking, milliseconds);
+    }
+
+    /**
+     * Start active braking on this motor. After a short time, the motor will turn off.
+     */
+    startBraking () {
+        this._parent._send('motorBrake', {motorIndex: this._index});
+        this._isOn = false;
+        this._setNewTimeout(this.setMotorOff, WeDo2Motor.BRAKE_TIME_MS);
+    }
+
+    /**
+     * Turn this motor off.
+     */
+    setMotorOff () {
+        this._parent._send('motorOff', {motorIndex: this._index});
+        this._isOn = false;
+    }
+
+    /**
+     * Clear the motor action timeout, if any. Safe to call even when there is no pending timeout.
+     * @private
+     */
+    _clearTimeout () {
+        if (this._pendingTimeoutId !== null) {
+            clearTimeout(this._pendingTimeoutId);
+            this._pendingTimeoutId = null;
+        }
+    }
+
+    /**
+     * Set a new motor action timeout, after clearing an existing one if necessary.
+     * @param {Function} callback - to be called at the end of the timeout.
+     * @param {int} delay - wait this many milliseconds before calling the callback.
+     * @private
+     */
+    _setNewTimeout (callback, delay) {
+        this._clearTimeout();
+        const timeoutID = setTimeout(() => {
+            if (this._pendingTimeoutId === timeoutID) {
+                this._pendingTimeoutId = null;
+            }
+            callback();
+        }, delay);
+        this._pendingTimeoutId = timeoutID;
+    }
+}
+
+/**
+ * Manage communication with a WeDo 2.0 device over a Device Manager client socket.
+ */
+class WeDo2 {
+
+    /**
+     * @return {string} - the type of Device Manager device socket that this class will handle.
+     */
+    static get DEVICE_TYPE () {
+        return 'wedo2';
+    }
+
+    /**
+     * Construct a WeDo2 communication object.
+     * @param {Socket} socket - the socket for a WeDo 2.0 device, as provided by a Device Manager client.
+     */
+    constructor (socket) {
+        /**
+         * The socket-IO socket used to communicate with the Device Manager about this device.
+         * @type {Socket}
+         * @private
+         */
+        this._socket = socket;
+
+        /**
+         * The motors which this WeDo 2.0 could possibly have.
+         * @type {[WeDo2Motor]}
+         * @private
+         */
+        this._motors = [new WeDo2Motor(this, 0), new WeDo2Motor(this, 1)];
+
+        /**
+         * The most recently received value for each sensor.
+         * @type {Object.<string, number>}
+         * @private
+         */
+        this._sensors = {
+            tiltX: 0,
+            tiltY: 0,
+            distance: 0
+        };
+
+        this._onSensorChanged = this._onSensorChanged.bind(this);
+        this._onDisconnect = this._onDisconnect.bind(this);
+
+        this._connectEvents();
+    }
+
+    /**
+     * Manually dispose of this object.
+     */
+    dispose () {
+        this._disconnectEvents();
+    }
+
+    /**
+     * @return {number} - the latest value received for the tilt sensor's tilt about the X axis.
+     */
+    get tiltX () {
+        return this._sensors.tiltX;
+    }
+
+    /**
+     * @return {number} - the latest value received for the tilt sensor's tilt about the Y axis.
+     */
+    get tiltY () {
+        return this._sensors.tiltY;
+    }
+
+    /**
+     * @return {number} - the latest value received from the distance sensor.
+     */
+    get distance () {
+        return this._sensors.distance;
+    }
+
+    /**
+     * Access a particular motor on this device.
+     * @param {int} index - the zero-based index of the desired motor.
+     * @return {WeDo2Motor} - the WeDo2Motor instance, if any, at that index.
+     */
+    motor (index) {
+        return this._motors[index];
+    }
+
+    /**
+     * Set the WeDo 2.0 hub's LED to a specific color.
+     * @param {int} rgb - a 24-bit RGB color in 0xRRGGBB format.
+     */
+    setLED (rgb) {
+        this._send('setLED', {rgb});
+    }
+
+    /**
+     * Play a tone from the WeDo 2.0 hub for a specific amount of time.
+     * @param {int} tone - the pitch of the tone, in Hz.
+     * @param {int} milliseconds - the duration of the note, in milliseconds.
+     */
+    playTone (tone, milliseconds) {
+        this._send('playTone', {tone, ms: milliseconds});
+    }
+
+    /**
+     * Stop the tone playing from the WeDo 2.0 hub, if any.
+     */
+    stopTone () {
+        this._send('stopTone');
+    }
+
+    /**
+     * Attach event handlers to the device socket.
+     * @private
+     */
+    _connectEvents () {
+        this._socket.on('sensorChanged', this._onSensorChanged);
+        this._socket.on('deviceWasClosed', this._onDisconnect);
+        this._socket.on('disconnect', this._onDisconnect);
+    }
+
+    /**
+     * Detach event handlers from the device socket.
+     * @private
+     */
+    _disconnectEvents () {
+        this._socket.off('sensorChanged', this._onSensorChanged);
+        this._socket.off('deviceWasClosed', this._onDisconnect);
+        this._socket.off('disconnect', this._onDisconnect);
+    }
+
+    /**
+     * Store the sensor value from an incoming 'sensorChanged' event.
+     * @param {object} event - the 'sensorChanged' event.
+     * @property {string} sensorName - the name of the sensor which changed.
+     * @property {number} sensorValue - the new value of the sensor.
+     * @private
+     */
+    _onSensorChanged (event) {
+        this._sensors[event.sensorName] = event.sensorValue;
+    }
+
+    /**
+     * React to device disconnection. May be called more than once.
+     * @private
+     */
+    _onDisconnect () {
+        this._disconnectEvents();
+    }
+
+    /**
+     * Send a message to the device socket.
+     * @param {string} message - the name of the message, such as 'playTone'.
+     * @param {object} [details] - optional additional details for the message, such as tone duration and pitch.
+     * @private
+     */
+    _send (message, details) {
+        this._socket.emit(message, details);
+    }
+}
+
+/**
+ * Enum for motor specification.
+ * @readonly
+ * @enum {string}
+ */
+const MotorID = {
+    DEFAULT: 'motor',
+    A: 'motor A',
+    B: 'motor B',
+    ALL: 'all motors'
+};
+
+/**
+ * Enum for motor direction specification.
+ * @readonly
+ * @enum {string}
+ */
+const MotorDirection = {
+    FORWARD: 'this way',
+    BACKWARD: 'that way',
+    REVERSE: 'reverse'
+};
+
+/**
+ * Enum for tilt sensor direction.
+ * @readonly
+ * @enum {string}
+ */
+const TiltDirection = {
+    UP: 'up',
+    DOWN: 'down',
+    LEFT: 'left',
+    RIGHT: 'right',
+    ANY: 'any'
+};
+
+/**
+ * Scratch 3.0 blocks to interact with a LEGO WeDo 2.0 device.
+ */
+class Scratch3WeDo2Blocks {
+
+    /**
+     * @return {string} - the name of this extension.
+     */
+    static get EXTENSION_NAME () {
+        return 'wedo2';
+    }
+
+    /**
+     * @return {number} - the tilt sensor counts as "tilted" if its tilt angle meets or exceeds this threshold.
+     */
+    static get TILT_THRESHOLD () {
+        return 15;
+    }
+
+    /**
+     * Construct a set of WeDo 2.0 blocks.
+     * @param {Runtime} runtime - the Scratch 3.0 runtime.
+     */
+    constructor (runtime) {
+        /**
+         * The Scratch 3.0 runtime.
+         * @type {Runtime}
+         */
+        this.runtime = runtime;
+
+        this.runtime.HACK_WeDo2Blocks = this;
+    }
+
+    /**
+     * Use the Device Manager client to attempt to connect to a WeDo 2.0 device.
+     */
+    connect () {
+        if (this._device || this._finder) {
+            return;
+        }
+        const deviceManager = this.runtime.ioDevices.deviceManager;
+        const finder = this._finder =
+            deviceManager.searchAndConnect(Scratch3WeDo2Blocks.EXTENSION_NAME, WeDo2.DEVICE_TYPE);
+        this._finder.promise.then(
+            socket => {
+                if (this._finder === finder) {
+                    this._finder = null;
+                    this._device = new WeDo2(socket);
+                } else {
+                    log.warn('Ignoring success from stale WeDo 2.0 connection attempt');
+                }
+            },
+            reason => {
+                if (this._finder === finder) {
+                    this._finder = null;
+                    log.warn(`WeDo 2.0 connection failed: ${reason}`);
+                } else {
+                    log.warn('Ignoring failure from stale WeDo 2.0 connection attempt');
+                }
+            });
+    }
+
+    /**
+     * Retrieve the block primitives implemented by this package.
+     * @return {object.<string, Function>} Mapping of opcode to Function.
+     */
+    getPrimitives () {
+        return {
+            wedo2_motorOnFor: this.motorOnFor,
+            wedo2_motorOn: this.motorOn,
+            wedo2_motorOff: this.motorOff,
+            wedo2_startMotorPower: this.startMotorPower,
+            wedo2_setMotorDirection: this.setMotorDirection,
+            wedo2_setLightHue: this.setLightHue,
+            wedo2_playNoteFor: this.playNoteFor,
+            wedo2_whenDistance: this.whenDistance,
+            wedo2_whenTilted: this.whenTilted,
+            wedo2_getDistance: this.getDistance,
+            wedo2_isTilted: this.isTilted,
+            wedo2_getTiltAngle: this.getTiltAngle
+        };
+    }
+
+    /**
+     * Turn specified motor(s) on for a specified duration.
+     * @param {object} args - the block's arguments.
+     * @property {MotorID} MOTOR_ID - the motor(s) to activate.
+     * @property {int} DURATION - the amount of time to run the motors.
+     * @return {Promise} - a promise which will resolve at the end of the duration.
+     */
+    motorOnFor (args) {
+        const durationMS = args.DURATION * 1000;
+        return new Promise(resolve => {
+            this._forEachMotor(args.MOTOR_ID, motorIndex => {
+                this._device.motor(motorIndex).setMotorOnFor(durationMS);
+            });
+
+            // Ensure this block runs for a fixed amount of time even when no device is connected.
+            setTimeout(resolve, durationMS);
+        });
+    }
+
+    /**
+     * Turn specified motor(s) on indefinitely.
+     * @param {object} args - the block's arguments.
+     * @property {MotorID} MOTOR_ID - the motor(s) to activate.
+     */
+    motorOn (args) {
+        this._forEachMotor(args.MOTOR_ID, motorIndex => {
+            this._device.motor(motorIndex).setMotorOn();
+        });
+    }
+
+    /**
+     * Turn specified motor(s) off.
+     * @param {object} args - the block's arguments.
+     * @property {MotorID} MOTOR_ID - the motor(s) to deactivate.
+     */
+    motorOff (args) {
+        this._forEachMotor(args.MOTOR_ID, motorIndex => {
+            this._device.motor(motorIndex).setMotorOff();
+        });
+    }
+
+    /**
+     * Turn specified motor(s) off.
+     * @param {object} args - the block's arguments.
+     * @property {MotorID} MOTOR_ID - the motor(s) to be affected.
+     * @property {int} POWER - the new power level for the motor(s).
+     */
+    startMotorPower (args) {
+        this._forEachMotor(args.MOTOR_ID, motorIndex => {
+            const motor = this._device.motor(motorIndex);
+            motor.power = args.POWER;
+            motor.setMotorOn();
+        });
+    }
+
+    /**
+     * Set the direction of rotation for specified motor(s).
+     * If the direction is 'reverse' the motor(s) will be reversed individually.
+     * @param {object} args - the block's arguments.
+     * @property {MotorID} MOTOR_ID - the motor(s) to be affected.
+     * @property {MotorDirection} DIRECTION - the new direction for the motor(s).
+     */
+    setMotorDirection (args) {
+        this._forEachMotor(args.MOTOR_ID, motorIndex => {
+            const motor = this._device.motor(motorIndex);
+            switch (args.DIRECTION) {
+            case MotorDirection.FORWARD:
+                motor.direction = 1;
+                break;
+            case MotorDirection.BACKWARD:
+                motor.direction = -1;
+                break;
+            case MotorDirection.REVERSE:
+                motor.direction = -motor.direction;
+                break;
+            default:
+                log.warn(`Unknown motor direction in setMotorDirection: ${args.DIRECTION}`);
+                break;
+            }
+        });
+    }
+
+    /**
+     * Set the LED's hue.
+     * @param {object} args - the block's arguments.
+     * @property {number} HUE - the hue to set, in the range [0,100].
+     */
+    setLightHue (args) {
+        // Convert from [0,100] to [0,360]
+        const hue = args.HUE * 360 / 100;
+
+        const rgbObject = color.hsvToRgb({h: hue, s: 1, v: 1});
+
+        const rgbDecimal = color.rgbToDecimal(rgbObject);
+
+        this._device.setLED(rgbDecimal);
+    }
+
+    /**
+     * Make the WeDo 2.0 hub play a MIDI note for the specified duration.
+     * @param {object} args - the block's arguments.
+     * @property {number} NOTE - the MIDI note to play.
+     * @property {number} DURATION - the duration of the note, in seconds.
+     * @return {Promise} - a promise which will resolve at the end of the duration.
+     */
+    playNoteFor (args) {
+        return new Promise(resolve => {
+            const durationMS = args.DURATION * 1000;
+            const tone = this._noteToTone(args.NOTE);
+            this._device.playTone(tone, durationMS);
+
+            // Ensure this block runs for a fixed amount of time even when no device is connected.
+            setTimeout(resolve, durationMS);
+        });
+    }
+
+    /**
+     * Compare the distance sensor's value to a reference.
+     * @param {object} args - the block's arguments.
+     * @property {string} OP - the comparison operation: '<' or '>'.
+     * @property {number} REFERENCE - the value to compare against.
+     * @return {boolean} - the result of the comparison, or false on error.
+     */
+    whenDistance (args) {
+        switch (args.OP) {
+        case '<':
+            return this._device.distance < args.REFERENCE;
+        case '>':
+            return this._device.distance > args.REFERENCE;
+        default:
+            log.warn(`Unknown comparison operator in whenDistance: ${args.OP}`);
+            return false;
+        }
+    }
+
+    /**
+     * Test whether the tilt sensor is currently tilted.
+     * @param {object} args - the block's arguments.
+     * @property {TiltDirection} DIRECTION - the tilt direction to test (up, down, left, right, or any).
+     * @return {boolean} - true if the tilt sensor is tilted past a threshold in the specified direction.
+     */
+    whenTilted (args) {
+        return this._isTilted(args.DIRECTION);
+    }
+
+    /**
+     * @return {number} - the distance sensor's value, scaled to the [0,100] range.
+     */
+    getDistance () {
+        return this._device.distance * 10;
+    }
+
+    /**
+     * Test whether the tilt sensor is currently tilted.
+     * @param {object} args - the block's arguments.
+     * @property {TiltDirection} DIRECTION - the tilt direction to test (up, down, left, right, or any).
+     * @return {boolean} - true if the tilt sensor is tilted past a threshold in the specified direction.
+     */
+    isTilted (args) {
+        return this._isTilted(args.DIRECTION);
+    }
+
+    /**
+     * @param {object} args - the block's arguments.
+     * @property {TiltDirection} DIRECTION - the direction (up, down, left, right) to check.
+     * @return {number} - the tilt sensor's angle in the specified direction.
+     * Note that getTiltAngle(up) = -getTiltAngle(down) and getTiltAngle(left) = -getTiltAngle(right).
+     */
+    getTiltAngle (args) {
+        return this._getTiltAngle(args.DIRECTION);
+    }
+
+    /**
+     * Test whether the tilt sensor is currently tilted.
+     * @param {TiltDirection} direction - the tilt direction to test (up, down, left, right, or any).
+     * @return {boolean} - true if the tilt sensor is tilted past a threshold in the specified direction.
+     * @private
+     */
+    _isTilted (direction) {
+        switch (direction) {
+        case TiltDirection.ANY:
+            return (Math.abs(this._device.tiltX) >= Scratch3WeDo2Blocks.TILT_THRESHOLD) ||
+                (Math.abs(this._device.tiltY) >= Scratch3WeDo2Blocks.TILT_THRESHOLD);
+        default:
+            return this._getTiltAngle(direction) >= Scratch3WeDo2Blocks.TILT_THRESHOLD;
+        }
+    }
+
+    /**
+     * @param {TiltDirection} direction - the direction (up, down, left, right) to check.
+     * @return {number} - the tilt sensor's angle in the specified direction.
+     * Note that getTiltAngle(up) = -getTiltAngle(down) and getTiltAngle(left) = -getTiltAngle(right).
+     * @private
+     */
+    _getTiltAngle (direction) {
+        switch (direction) {
+        case TiltDirection.UP:
+            return -this._device.tiltY;
+        case TiltDirection.DOWN:
+            return this._device.tiltY;
+        case TiltDirection.LEFT:
+            return -this._device.tiltX;
+        case TiltDirection.RIGHT:
+            return this._device.tiltX;
+        default:
+            log.warn(`Unknown tilt direction in _getTiltAngle: ${direction}`);
+        }
+    }
+
+    /**
+     * Call a callback for each motor indexed by the provided motor ID.
+     * @param {MotorID} motorID - the ID specifier.
+     * @param {Function} callback - the function to call with the numeric motor index for each motor.
+     * @private
+     */
+    _forEachMotor (motorID, callback) {
+        let motors;
+        switch (motorID) {
+        case MotorID.A:
+            motors = [0];
+            break;
+        case MotorID.B:
+            motors = [1];
+            break;
+        case MotorID.ALL:
+        case MotorID.DEFAULT:
+            motors = [0, 1];
+            break;
+        default:
+            log.warn(`Invalid motor ID: ${motorID}`);
+            motors = [];
+            break;
+        }
+        for (const index of motors) {
+            callback(index);
+        }
+    }
+
+    /**
+     * @param {number} midiNote - the MIDI note value to convert.
+     * @return {number} - the frequency, in Hz, corresponding to that MIDI note value.
+     * @private
+     */
+    _noteToTone (midiNote) {
+        // Note that MIDI note 69 is A4, 440 Hz
+        return 440 * Math.pow(2, (midiNote - 69) / 12);
+    }
+}
+
+module.exports = Scratch3WeDo2Blocks;
diff --git a/src/engine/runtime.js b/src/engine/runtime.js
index 7756ceb1..80a40400 100644
--- a/src/engine/runtime.js
+++ b/src/engine/runtime.js
@@ -20,7 +20,8 @@ const defaultBlockPackages = {
     scratch3_sound: require('../blocks/scratch3_sound'),
     scratch3_sensing: require('../blocks/scratch3_sensing'),
     scratch3_data: require('../blocks/scratch3_data'),
-    scratch3_procedures: require('../blocks/scratch3_procedures')
+    scratch3_procedures: require('../blocks/scratch3_procedures'),
+    scratch3_wedo2: require('../blocks/scratch3_wedo2')
 };
 
 /**