diff --git a/src/blocks/scratch3_looks.js b/src/blocks/scratch3_looks.js
index 70238a786..a64f095b0 100644
--- a/src/blocks/scratch3_looks.js
+++ b/src/blocks/scratch3_looks.js
@@ -242,6 +242,15 @@ class Scratch3LooksBlocks {
         };
     }
 
+    getMonitored () {
+        return {
+            size: {isSpriteSpecific: true},
+            costumeorder: {isSpriteSpecific: true},
+            backdroporder: {},
+            backdropname: {}
+        };
+    }
+
     say (args, util) {
         // @TODO in 2.0 calling say/think resets the right/left bias of the bubble
         this._updateBubble(util.target, 'say', String(args.MESSAGE));
diff --git a/src/blocks/scratch3_motion.js b/src/blocks/scratch3_motion.js
index d040337c8..b30138d3e 100644
--- a/src/blocks/scratch3_motion.js
+++ b/src/blocks/scratch3_motion.js
@@ -38,6 +38,14 @@ class Scratch3MotionBlocks {
         };
     }
 
+    getMonitored () {
+        return {
+            xposition: {isSpriteSpecific: true},
+            yposition: {isSpriteSpecific: true},
+            direction: {isSpriteSpecific: true}
+        };
+    }
+
     moveSteps (args, util) {
         const steps = Cast.toNumber(args.STEPS);
         const radians = MathUtil.degToRad(90 - util.target.direction);
diff --git a/src/blocks/scratch3_sensing.js b/src/blocks/scratch3_sensing.js
index 17dc87e9d..d51dd5d3b 100644
--- a/src/blocks/scratch3_sensing.js
+++ b/src/blocks/scratch3_sensing.js
@@ -49,6 +49,16 @@ class Scratch3SensingBlocks {
         };
     }
 
+    getMonitored () {
+        return {
+            answer: {},
+            loudness: {},
+            timer: {},
+            of: {},
+            current: {}
+        };
+    }
+
     _onAnswer (answer) {
         this._answer = answer;
         const questionObj = this._questionList.shift();
diff --git a/src/blocks/scratch3_sound.js b/src/blocks/scratch3_sound.js
index 6f5fed972..d3f3f92ac 100644
--- a/src/blocks/scratch3_sound.js
+++ b/src/blocks/scratch3_sound.js
@@ -103,6 +103,12 @@ class Scratch3SoundBlocks {
         };
     }
 
+    getMonitored () {
+        return {
+            volume: {}
+        };
+    }
+
     playSound (args, util) {
         const index = this._getSoundIndex(args.SOUND_MENU, util);
         if (index >= 0) {
diff --git a/src/engine/runtime.js b/src/engine/runtime.js
index 6d650668e..d8fa88358 100644
--- a/src/engine/runtime.js
+++ b/src/engine/runtime.js
@@ -176,6 +176,13 @@ class Runtime extends EventEmitter {
          */
         this._refreshTargets = false;
 
+        /**
+         * Map to look up all monitor block information by opcode.
+         * @type {object}
+         * @private
+         */
+        this.monitorBlockInfo = {};
+
         /**
          * Ordered map of all monitors, which are MonitorReporter objects.
          */
@@ -225,6 +232,9 @@ class Runtime extends EventEmitter {
         // Register all given block packages.
         this._registerBlockPackages();
 
+        // Populate monitorBlockInfo
+        this._registerMonitorInfo();
+
         // Register and initialize "IO devices", containers for processing
         // I/O related data.
         /** @type {Object.<string, Object>} */
@@ -451,6 +461,22 @@ class Runtime extends EventEmitter {
         this.emit(Runtime.EXTENSION_ADDED, categoryInfo.blocks.concat(categoryInfo.menus));
     }
 
+    /**
+     * Populate this.monitorBlockInfo
+     */
+    _registerMonitorInfo () {
+        for (const packageName in defaultBlockPackages) {
+            if (defaultBlockPackages.hasOwnProperty(packageName)) {
+                // @todo pass a different runtime depending on package privilege?
+                const packageObject = new (defaultBlockPackages[packageName])(this);
+                // Collect monitored from package.
+                if (packageObject.getMonitored) {
+                    this.monitorBlockInfo = Object.assign({}, this.monitorBlockInfo, packageObject.getMonitored());
+                }
+            }
+        }
+    }
+
     /**
      * Build the scratch-blocks JSON for a menu. Note that scratch-blocks treats menus as a special kind of block.
      * @param {string} menuName - the name of the menu
diff --git a/src/virtual-machine.js b/src/virtual-machine.js
index 175b5fd20..5c5361bae 100644
--- a/src/virtual-machine.js
+++ b/src/virtual-machine.js
@@ -575,44 +575,18 @@ class VirtualMachine extends EventEmitter {
      * @param {!Blockly.Event} e Any Blockly event.
      */
     monitorBlockListener (e) {
-        const tempMonitoredBlocks = [
-            'volume',
-            'tempo',
-            'answer',
-            'loudness',
-            'videoon',
-            'timer',
-            'of',
-            'current',
-            'username',
-            'xposition',
-            'yposition',
-            'direction',
-            'size',
-            'backdropname',
-            'costumeorder',
-            'backdroporder'
-        ];
-        const tempMonitoredPerSpriteBlocks = [
-            'xposition',
-            'yposition',
-            'direction',
-            'size',
-            'costumeorder'
-        ];
         // Filter events by type, since monitor blocks only need to listen to these events.
         // Monitor blocks shouldn't be destroyed when flyout blocks are deleted.
         if (['create', 'change'].indexOf(e.type) !== -1) {
-            // TEMPORARY ----
             let blockType = e.blockId.split('_');
             blockType = blockType[blockType.length - 1];
-            if (tempMonitoredBlocks.indexOf(blockType) === -1) {
+            if (!this.runtime.monitorBlockInfo.hasOwnProperty(blockType)) {
                 return;
             }
-            if (tempMonitoredPerSpriteBlocks.indexOf(blockType) !== -1) {
+            if (!this.runtime.monitorBlockInfo.hasOwnProperty(blockType) ||
+                this.runtime.monitorBlockInfo[blockType].isSpriteSpecific) {
                 e.isSpriteSpecific = true;
             }
-            // -----
             this.runtime.monitorBlocks.blocklyListen(e, this.runtime);
         }
     }