diff --git a/include/app/ModuleWidget.hpp b/include/app/ModuleWidget.hpp
index 7aea4442..371793ee 100644
--- a/include/app/ModuleWidget.hpp
+++ b/include/app/ModuleWidget.hpp
@@ -111,6 +111,7 @@ struct ModuleWidget : widget::OpaqueWidget {
 	INTERNAL bool& dragEnabled();
 	INTERNAL math::Vec& oldPos();
 	INTERNAL engine::Module* releaseModule();
+	INTERNAL bool& selected();
 };
 
 
diff --git a/include/app/RackWidget.hpp b/include/app/RackWidget.hpp
index e43f476b..1e692c4b 100644
--- a/include/app/RackWidget.hpp
+++ b/include/app/RackWidget.hpp
@@ -38,8 +38,12 @@ struct RackWidget : widget::OpaqueWidget {
 
 	void onHover(const HoverEvent& e) override;
 	void onHoverKey(const HoverKeyEvent& e) override;
-	void onDragHover(const DragHoverEvent& e) override;
 	void onButton(const ButtonEvent& e) override;
+	void onDragStart(const DragStartEvent& e) override;
+	void onDragEnd(const DragEndEvent& e) override;
+	void onDragHover(const DragHoverEvent& e) override;
+
+	// Rack methods
 
 	/** Completely clear the rack's modules and cables */
 	void clear();
@@ -65,6 +69,7 @@ struct RackWidget : widget::OpaqueWidget {
 	bool isEmpty();
 	void updateModuleOldPositions();
 	history::ComplexAction* getModuleDragAction();
+	void updateModuleSelections();
 
 	// Cable methods
 
diff --git a/include/math.hpp b/include/math.hpp
index 6545e1a1..330a1c96 100644
--- a/include/math.hpp
+++ b/include/math.hpp
@@ -308,10 +308,16 @@ struct Rect {
 	Rect() {}
 	Rect(Vec pos, Vec size) : pos(pos), size(size) {}
 	Rect(float posX, float posY, float sizeX, float sizeY) : pos(Vec(posX, posY)), size(Vec(sizeX, sizeY)) {}
-	/** Constructs a Rect from the upper-left position `a` and lower-right pos `b`. */
+	/** Constructs a Rect from a top-left and bottom-right vector.
+	*/
 	static Rect fromMinMax(Vec a, Vec b) {
 		return Rect(a, b.minus(a));
 	}
+	/** Constructs a Rect from any two opposite corners.
+	*/
+	static Rect fromCorners(Vec a, Vec b) {
+		return fromMinMax(a.min(b), a.max(b));
+	}
 	/** Returns the infinite Rect. */
 	static Rect inf() {
 		return Rect(Vec(-INFINITY, -INFINITY), Vec(INFINITY, INFINITY));
diff --git a/src/app/ModuleWidget.cpp b/src/app/ModuleWidget.cpp
index fdc7fb2a..7fbb9f37 100644
--- a/src/app/ModuleWidget.cpp
+++ b/src/app/ModuleWidget.cpp
@@ -418,6 +418,8 @@ struct ModuleWidget::Internal {
 	math::Vec oldPos;
 
 	widget::Widget* panel = NULL;
+
+	bool selected = false;
 };
 
 
@@ -597,6 +599,17 @@ void ModuleWidget::draw(const DrawArgs& args) {
 	// 	bndLabel(args.vg, 0, 0, INFINITY, INFINITY, -1, debugText.c_str());
 	// }
 
+	// Selection
+	if (internal->selected) {
+		nvgBeginPath(args.vg);
+		nvgRect(args.vg, 0.0, 0.0, VEC_ARGS(box.size));
+		nvgFillColor(args.vg, nvgRGBAf(1, 0, 0, 0.25));
+		nvgFill(args.vg);
+		nvgStrokeWidth(args.vg, 2.0);
+		nvgStrokeColor(args.vg, nvgRGBAf(1, 0, 0, 0.5));
+		nvgStroke(args.vg);
+	}
+
 	nvgResetScissor(args.vg);
 }
 
@@ -1210,5 +1223,11 @@ engine::Module* ModuleWidget::releaseModule() {
 }
 
 
+bool& ModuleWidget::selected() {
+	return internal->selected;
+}
+
+
+
 } // namespace app
 } // namespace rack
\ No newline at end of file
diff --git a/src/app/RackWidget.cpp b/src/app/RackWidget.cpp
index ad191256..08da83fc 100644
--- a/src/app/RackWidget.cpp
+++ b/src/app/RackWidget.cpp
@@ -72,12 +72,15 @@ struct CableContainer : widget::TransparentWidget {
 };
 
 
-// struct RackWidget::Internal {
-// };
+struct RackWidget::Internal {
+	bool selecting = false;
+	math::Vec selectionStart;
+	math::Vec selectionEnd;
+};
 
 
 RackWidget::RackWidget() {
-	// internal = new Internal;
+	internal = new Internal;
 
 	rail = new RailWidget;
 	addChild(rail);
@@ -91,7 +94,7 @@ RackWidget::RackWidget() {
 
 RackWidget::~RackWidget() {
 	clear();
-	// delete internal;
+	delete internal;
 }
 
 void RackWidget::step() {
@@ -104,11 +107,24 @@ void RackWidget::draw(const DrawArgs& args) {
 	nvgGlobalTint(args.vg, nvgRGBAf(b, b, b, 1));
 
 	Widget::draw(args);
+
+	// Draw selection rectangle
+	if (internal->selecting) {
+		nvgBeginPath(args.vg);
+		math::Rect selectionBox = math::Rect::fromCorners(internal->selectionStart, internal->selectionEnd);
+		nvgRect(args.vg, RECT_ARGS(selectionBox));
+		nvgFillColor(args.vg, nvgRGBAf(1, 0, 0, 0.25));
+		nvgFill(args.vg);
+		nvgStrokeWidth(args.vg, 2.0);
+		nvgStrokeColor(args.vg, nvgRGBAf(1, 0, 0, 0.5));
+		nvgStroke(args.vg);
+	}
 }
 
 void RackWidget::onHover(const HoverEvent& e) {
 	// Set before calling children's onHover()
 	mousePos = e.pos;
+
 	OpaqueWidget::onHover(e);
 }
 
@@ -125,12 +141,6 @@ void RackWidget::onHoverKey(const HoverKeyEvent& e) {
 	}
 }
 
-void RackWidget::onDragHover(const DragHoverEvent& e) {
-	// Set before calling children's onDragHover()
-	mousePos = e.pos;
-	OpaqueWidget::onDragHover(e);
-}
-
 void RackWidget::onButton(const ButtonEvent& e) {
 	Widget::onButton(e);
 	e.stopPropagating();
@@ -141,6 +151,37 @@ void RackWidget::onButton(const ButtonEvent& e) {
 		APP->scene->moduleBrowser->show();
 		e.consume(this);
 	}
+	if (e.action == GLFW_PRESS && e.button == GLFW_MOUSE_BUTTON_LEFT) {
+		e.consume(this);
+	}
+}
+
+void RackWidget::onDragStart(const DragStartEvent& e) {
+	if (e.button == GLFW_MOUSE_BUTTON_LEFT) {
+		// Deselect all modules
+		updateModuleSelections();
+		internal->selecting = true;
+		internal->selectionStart = mousePos;
+		internal->selectionEnd = mousePos;
+	}
+}
+
+void RackWidget::onDragEnd(const DragEndEvent& e) {
+	if (e.button == GLFW_MOUSE_BUTTON_LEFT) {
+		internal->selecting = false;
+	}
+}
+
+void RackWidget::onDragHover(const DragHoverEvent& e) {
+	// Set before calling children's onDragHover()
+	mousePos = e.pos;
+
+	if (internal->selecting) {
+		internal->selectionEnd = mousePos;
+		updateModuleSelections();
+	}
+
+	OpaqueWidget::onDragHover(e);
 }
 
 void RackWidget::clear() {
@@ -590,6 +631,15 @@ history::ComplexAction* RackWidget::getModuleDragAction() {
 	return h;
 }
 
+void RackWidget::updateModuleSelections() {
+	math::Rect selectionBox = math::Rect::fromCorners(internal->selectionStart, internal->selectionEnd);
+	for (widget::Widget* w : moduleContainer->children) {
+		ModuleWidget* mw = dynamic_cast<ModuleWidget*>(w);
+		assert(mw);
+		bool selected = internal->selecting && selectionBox.intersects(mw->box);
+		mw->selected() = selected;
+	}
+}
 
 void RackWidget::clearCables() {
 	incompleteCable = NULL;