diff --git a/interface/CMakeLists.txt b/interface/CMakeLists.txt
index 800cadf72f..84aa0328b0 100644
--- a/interface/CMakeLists.txt
+++ b/interface/CMakeLists.txt
@@ -44,7 +44,7 @@ else ()
 endif ()
 
 find_package(Qt5 COMPONENTS
-    Gui Multimedia Network OpenGL Qml Quick Script Svg
+    Gui Multimedia Network OpenGL Qml Quick Script ScriptTools Svg
     WebChannel WebEngine WebEngineWidgets WebKitWidgets WebSockets)
 
 # grab the ui files in resources/ui
@@ -201,7 +201,7 @@ include_directories("${PROJECT_SOURCE_DIR}/src")
 target_link_libraries(
   ${TARGET_NAME}
   Qt5::Gui Qt5::Network Qt5::Multimedia Qt5::OpenGL
-  Qt5::Qml Qt5::Quick Qt5::Script Qt5::Svg
+  Qt5::Qml Qt5::Quick Qt5::Script Qt5::ScriptTools Qt5::Svg
   Qt5::WebChannel Qt5::WebEngine Qt5::WebEngineWidgets Qt5::WebKitWidgets
 )
 
diff --git a/interface/src/scripting/MenuScriptingInterface.cpp b/interface/src/scripting/MenuScriptingInterface.cpp
index da55a8829f..7eb80b5946 100644
--- a/interface/src/scripting/MenuScriptingInterface.cpp
+++ b/interface/src/scripting/MenuScriptingInterface.cpp
@@ -11,8 +11,11 @@
 
 #include "MenuScriptingInterface.h"
 
-#include "Menu.h"
+#include <QtCore/QCoreApplication>
+#include <QtCore/QThread>
+
 #include <MenuItemProperties.h>
+#include "Menu.h"
 
 MenuScriptingInterface* MenuScriptingInterface::getInstance() {
     static MenuScriptingInterface sharedInstance;
@@ -36,6 +39,9 @@ void MenuScriptingInterface::removeMenu(const QString& menu) {
 }
 
 bool MenuScriptingInterface::menuExists(const QString& menu) {
+    if (QThread::currentThread() == qApp->thread()) {
+        return Menu::getInstance()->menuExists(menu);
+    }
     bool result;
     QMetaObject::invokeMethod(Menu::getInstance(), "menuExists", Qt::BlockingQueuedConnection,
                 Q_RETURN_ARG(bool, result), 
@@ -76,11 +82,14 @@ void MenuScriptingInterface::removeMenuItem(const QString& menu, const QString&
 };
 
 bool MenuScriptingInterface::menuItemExists(const QString& menu, const QString& menuitem) {
+    if (QThread::currentThread() == qApp->thread()) {
+        return Menu::getInstance()->menuItemExists(menu, menuitem);
+    }
     bool result;
     QMetaObject::invokeMethod(Menu::getInstance(), "menuItemExists", Qt::BlockingQueuedConnection,
-                Q_RETURN_ARG(bool, result), 
-                Q_ARG(const QString&, menu),
-                Q_ARG(const QString&, menuitem));
+        Q_RETURN_ARG(bool, result),
+        Q_ARG(const QString&, menu),
+        Q_ARG(const QString&, menuitem));
     return result;
 }
 
@@ -101,6 +110,9 @@ void MenuScriptingInterface::removeActionGroup(const QString& groupName) {
 }
 
 bool MenuScriptingInterface::isOptionChecked(const QString& menuOption) {
+    if (QThread::currentThread() == qApp->thread()) {
+        return Menu::getInstance()->isOptionChecked(menuOption);
+    }
     bool result;
     QMetaObject::invokeMethod(Menu::getInstance(), "isOptionChecked", Qt::BlockingQueuedConnection,
                 Q_RETURN_ARG(bool, result), 
@@ -109,7 +121,7 @@ bool MenuScriptingInterface::isOptionChecked(const QString& menuOption) {
 }
 
 void MenuScriptingInterface::setIsOptionChecked(const QString& menuOption, bool isChecked) {
-    QMetaObject::invokeMethod(Menu::getInstance(), "setIsOptionChecked", Qt::BlockingQueuedConnection,
+    QMetaObject::invokeMethod(Menu::getInstance(), "setIsOptionChecked",
                 Q_ARG(const QString&, menuOption),
                 Q_ARG(bool, isChecked));
 }
diff --git a/libraries/script-engine/CMakeLists.txt b/libraries/script-engine/CMakeLists.txt
index 8ff13aba70..48fda99b9d 100644
--- a/libraries/script-engine/CMakeLists.txt
+++ b/libraries/script-engine/CMakeLists.txt
@@ -1,3 +1,3 @@
 set(TARGET_NAME script-engine)
-setup_hifi_library(Gui Network Script WebSockets Widgets)
+setup_hifi_library(Gui Network Script ScriptTools WebSockets Widgets)
 link_hifi_libraries(shared networking octree gpu ui procedural model model-networking recording avatars fbx entities controllers animation audio physics)
diff --git a/libraries/script-engine/src/ScriptEngine.cpp b/libraries/script-engine/src/ScriptEngine.cpp
index d1eaffd2c5..f7ac7894ff 100644
--- a/libraries/script-engine/src/ScriptEngine.cpp
+++ b/libraries/script-engine/src/ScriptEngine.cpp
@@ -17,12 +17,18 @@
 #include <QtCore/QFileInfo>
 #include <QtCore/QTimer>
 #include <QtCore/QThread>
+#include <QtCore/QRegularExpression>
+
+#include <QtWidgets/QMainWindow>
+#include <QtWidgets/QApplication>
+
 #include <QtNetwork/QNetworkRequest>
 #include <QtNetwork/QNetworkReply>
-#include <QtScript/QScriptEngine>
+
 #include <QtScript/QScriptValue>
 #include <QtScript/QScriptValueIterator>
-#include <QtCore/QStringList>
+
+#include <QtScriptTools/QScriptEngineDebugger>
 
 #include <AudioConstants.h>
 #include <AudioEffectOptions.h>
@@ -34,6 +40,7 @@
 #include <NodeList.h>
 #include <udt/PacketHeaders.h>
 #include <UUID.h>
+#include <ui/Menu.h>
 
 #include <controllers/ScriptingInterface.h>
 #include <AnimationObject.h>
@@ -169,6 +176,93 @@ void ScriptEngine::disconnectNonEssentialSignals() {
     }
 }
 
+void ScriptEngine::runDebuggable() {
+    static QMenuBar* menuBar { nullptr };
+    static QMenu* scriptDebugMenu { nullptr };
+    static size_t scriptMenuCount { 0 };
+    if (!scriptDebugMenu) {
+        for (auto window : qApp->topLevelWidgets()) {
+            auto mainWindow = qobject_cast<QMainWindow*>(window);
+            if (mainWindow) {
+                menuBar = mainWindow->menuBar();
+                break;
+            }
+        }
+        if (menuBar) {
+            scriptDebugMenu = menuBar->addMenu("Script Debug");
+        }
+    }
+
+    init();
+    _isRunning = true;
+    _debuggable = true;
+    _debugger = new QScriptEngineDebugger(this);
+    _debugger->attachTo(this);
+
+    QMenu* parentMenu = scriptDebugMenu;
+    QMenu* scriptMenu { nullptr };
+    if (parentMenu) {
+        ++scriptMenuCount;
+        scriptMenu = parentMenu->addMenu(_fileNameString);
+        scriptMenu->addMenu(_debugger->createStandardMenu(qApp->activeWindow()));
+    } else {
+        qWarning() << "Unable to add script debug menu";
+    }
+
+    QScriptValue result = evaluate(_scriptContents, _fileNameString);
+
+    _lastUpdate = usecTimestampNow();
+    QTimer* timer = new QTimer(this);
+    connect(this, &ScriptEngine::finished, [this, timer, parentMenu, scriptMenu] {
+        if (scriptMenu) {
+            parentMenu->removeAction(scriptMenu->menuAction());
+            --scriptMenuCount;
+            if (0 == scriptMenuCount) {
+                menuBar->removeAction(scriptDebugMenu->menuAction());
+                scriptDebugMenu = nullptr;
+            }
+        }
+        disconnect(timer); 
+    });
+
+    connect(timer, &QTimer::timeout, [this, timer] {
+        if (_isFinished) {
+            if (!_isRunning) {
+                return;
+            }
+            stopAllTimers(); // make sure all our timers are stopped if the script is ending
+            if (_wantSignals) {
+                emit scriptEnding();
+                emit finished(_fileNameString, this);
+            }
+            _isRunning = false;
+            if (_wantSignals) {
+                emit runningStateChanged();
+                emit doneRunning();
+            }
+            timer->deleteLater();
+            return;
+        }
+
+        qint64 now = usecTimestampNow();
+        // we check for 'now' in the past in case people set their clock back
+        if (_lastUpdate < now) {
+            float deltaTime = (float)(now - _lastUpdate) / (float)USECS_PER_SECOND;
+            if (!_isFinished) {
+                if (_wantSignals) {
+                    emit update(deltaTime);
+                }
+            }
+        }
+        _lastUpdate = now;
+        // Debug and clear exceptions
+        hadUncaughtExceptions(*this, _fileNameString);
+    });
+
+    timer->start(10);
+}
+
+
 void ScriptEngine::runInThread() {
     Q_ASSERT_X(!_isThreaded, "ScriptEngine::runInThread()", "runInThread should not be called more than once");
 
@@ -260,6 +354,10 @@ void ScriptEngine::loadURL(const QUrl& scriptURL, bool reload) {
 // FIXME - switch this to the new model of ScriptCache callbacks
 void ScriptEngine::scriptContentsAvailable(const QUrl& url, const QString& scriptContents) {
     _scriptContents = scriptContents;
+    static const QString DEBUG_FLAG("#debug");
+    if (QRegularExpression(DEBUG_FLAG).match(scriptContents).hasMatch()) {
+        _debuggable = true;
+    }
     if (_wantSignals) {
         emit scriptLoaded(url.toString());
     }
@@ -723,7 +821,7 @@ void ScriptEngine::run() {
     auto nodeList = DependencyManager::get<NodeList>();
     auto entityScriptingInterface = DependencyManager::get<EntityScriptingInterface>();
 
-    qint64 lastUpdate = usecTimestampNow();
+    _lastUpdate = usecTimestampNow();
 
     // TODO: Integrate this with signals/slots instead of reimplementing throttling for ScriptEngine
     while (!_isFinished) {
@@ -771,15 +869,15 @@ void ScriptEngine::run() {
         qint64 now = usecTimestampNow();
 
         // we check for 'now' in the past in case people set their clock back
-        if (lastUpdate < now) {
-            float deltaTime = (float) (now - lastUpdate) / (float) USECS_PER_SECOND;
+        if (_lastUpdate < now) {
+            float deltaTime = (float) (now - _lastUpdate) / (float) USECS_PER_SECOND;
             if (!_isFinished) {
                 if (_wantSignals) {
                     emit update(deltaTime);
                 }
             }
         }
-        lastUpdate = now;
+        _lastUpdate = now;
 
         // Debug and clear exceptions
         hadUncaughtExceptions(*this, _fileNameString);
diff --git a/libraries/script-engine/src/ScriptEngine.h b/libraries/script-engine/src/ScriptEngine.h
index f050997235..d37e3eb177 100644
--- a/libraries/script-engine/src/ScriptEngine.h
+++ b/libraries/script-engine/src/ScriptEngine.h
@@ -18,9 +18,10 @@
 #include <QtCore/QUrl>
 #include <QtCore/QSet>
 #include <QtCore/QWaitCondition>
-#include <QtScript/QScriptEngine>
 #include <QtCore/QStringList>
 
+#include <QtScript/QScriptEngine>
+
 #include <AnimationCache.h>
 #include <AnimVariant.h>
 #include <AvatarData.h>
@@ -39,6 +40,8 @@
 #include "ScriptUUID.h"
 #include "Vec3.h"
 
+class QScriptEngineDebugger;
+
 static const QString NO_SCRIPT("");
 
 static const int SCRIPT_FPS = 60;
@@ -75,6 +78,8 @@ public:
     /// services before calling this.
     void runInThread();
 
+    void runDebuggable();
+
     /// run the script in the callers thread, exit when stop() is called.
     void run();
 
@@ -140,6 +145,8 @@ public:
     bool isFinished() const { return _isFinished; } // used by Application and ScriptWidget
     bool isRunning() const { return _isRunning; } // used by ScriptWidget
 
+    bool isDebuggable() const { return _debuggable; }
+
     void disconnectNonEssentialSignals();
 
     ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -187,6 +194,9 @@ protected:
     bool _wantSignals { true };
     QHash<EntityItemID, EntityScriptDetails> _entityScripts;
     bool _isThreaded { false };
+    QScriptEngineDebugger* _debugger { nullptr };
+    bool _debuggable { false };
+    qint64 _lastUpdate;
 
     void init();
     QString getFilename() const;
diff --git a/libraries/script-engine/src/ScriptEngines.cpp b/libraries/script-engine/src/ScriptEngines.cpp
index c6070e0598..cf82d9db4f 100644
--- a/libraries/script-engine/src/ScriptEngines.cpp
+++ b/libraries/script-engine/src/ScriptEngines.cpp
@@ -9,7 +9,8 @@
 #include "ScriptEngines.h"
 
 #include <QtCore/QStandardPaths>
-#include <QtCore/QCoreApplication>
+
+#include <QtWidgets/QApplication>
 
 #include <SettingHandle.h>
 #include <UserActivityLogger.h>
@@ -490,7 +491,12 @@ void ScriptEngines::launchScriptEngine(ScriptEngine* scriptEngine) {
     for (auto initializer : _scriptInitializers) {
         initializer(scriptEngine);
     }
-    scriptEngine->runInThread();
+    
+    if (scriptEngine->isDebuggable() || (qApp->queryKeyboardModifiers() & Qt::ShiftModifier)) {
+        scriptEngine->runDebuggable();
+    } else {
+        scriptEngine->runInThread();
+    }
 }