diff --git a/TODO.md b/TODO.md
index eaee38e68..b26c925a5 100644
--- a/TODO.md
+++ b/TODO.md
@@ -90,9 +90,9 @@ A step-by-step checklist for porting MatterControl's design features to a Vue +
 - [x] Implement click-to-select single object
 - [x] Implement click-on-empty to deselect
 - [x] Add `selectedObjects` array to Pinia store
-- [ ] Implement Shift+click for multi-select
-- [ ] Implement Ctrl+click to toggle selection
-- [ ] Add "Select All" (Ctrl+A) shortcut
+- [x] Implement Shift+click for multi-select
+- [x] Implement Ctrl+click to toggle selection
+- [x] Add "Select All" (Ctrl+A) shortcut
 
 ### Selection Visualization
 - [ ] Add selection outline effect (OutlinePass or custom)
diff --git a/src/App.vue b/src/App.vue
index 6d0f0b101..a55fe55e5 100644
--- a/src/App.vue
+++ b/src/App.vue
@@ -1,17 +1,39 @@
 <script setup lang="ts">
+import { onMounted, onUnmounted } from 'vue'
 import AppLayout from './components/AppLayout.vue'
 import Viewport from './components/Viewport.vue'
 import { useSceneStore, type SceneObject } from './stores/scene'
 
 const sceneStore = useSceneStore()
 
-function handlePick(object: SceneObject | null) {
+function handlePick(object: SceneObject | null, event: MouseEvent) {
   if (object) {
-    sceneStore.select(object.id)
+    if (event.shiftKey) {
+      sceneStore.addToSelection(object.id)
+    } else if (event.ctrlKey || event.metaKey) {
+      sceneStore.toggleSelection(object.id)
+    } else {
+      sceneStore.select(object.id)
+    }
   } else {
     sceneStore.clearSelection()
   }
 }
+
+function handleKeyDown(event: KeyboardEvent) {
+  if ((event.ctrlKey || event.metaKey) && event.key === 'a') {
+    event.preventDefault()
+    sceneStore.selectAll()
+  }
+}
+
+onMounted(() => {
+  window.addEventListener('keydown', handleKeyDown)
+})
+
+onUnmounted(() => {
+  window.removeEventListener('keydown', handleKeyDown)
+})
 </script>
 
 <template>
diff --git a/src/stores/scene.spec.ts b/src/stores/scene.spec.ts
index eb6f61131..7fa844f44 100644
--- a/src/stores/scene.spec.ts
+++ b/src/stores/scene.spec.ts
@@ -248,5 +248,68 @@ describe('useSceneStore', () => {
       expect(store.selectedObjects).toHaveLength(1)
       expect(store.selectedObjects[0]?.name).toBe('A')
     })
+
+    it('addToSelection() adds to existing selection', () => {
+      const obj1 = store.addObject(createTestMesh(), 'A')
+      const obj2 = store.addObject(createTestMesh(), 'B')
+
+      store.select(obj1.id)
+      store.addToSelection(obj2.id)
+
+      expect(store.selectedObjects).toHaveLength(2)
+    })
+
+    it('addToSelection() ignores locked objects', () => {
+      const obj1 = store.addObject(createTestMesh(), 'A')
+      const obj2 = store.addObject(createTestMesh(), 'B')
+      store.setObjectLocked(obj2.id, true)
+
+      store.select(obj1.id)
+      store.addToSelection(obj2.id)
+
+      expect(store.selectedObjects).toHaveLength(1)
+    })
+
+    it('toggleSelection() adds unselected object', () => {
+      const obj1 = store.addObject(createTestMesh(), 'A')
+      const obj2 = store.addObject(createTestMesh(), 'B')
+
+      store.select(obj1.id)
+      store.toggleSelection(obj2.id)
+
+      expect(store.selectedObjects).toHaveLength(2)
+    })
+
+    it('toggleSelection() removes selected object', () => {
+      const obj1 = store.addObject(createTestMesh(), 'A')
+      const obj2 = store.addObject(createTestMesh(), 'B')
+
+      store.select(obj1.id)
+      store.addToSelection(obj2.id)
+      store.toggleSelection(obj1.id)
+
+      expect(store.selectedObjects).toHaveLength(1)
+      expect(store.selectedObjects[0]?.id).toBe(obj2.id)
+    })
+
+    it('toggleSelection() ignores locked objects', () => {
+      const obj = store.addObject(createTestMesh(), 'A')
+      store.setObjectLocked(obj.id, true)
+
+      store.toggleSelection(obj.id)
+
+      expect(store.selectedObjects).toHaveLength(0)
+    })
+
+    it('selectAll() selects all unlocked objects', () => {
+      store.addObject(createTestMesh(), 'A')
+      store.addObject(createTestMesh(), 'B')
+      const obj3 = store.addObject(createTestMesh(), 'C')
+      store.setObjectLocked(obj3.id, true)
+
+      store.selectAll()
+
+      expect(store.selectedObjects).toHaveLength(2)
+    })
   })
 })
diff --git a/src/stores/scene.ts b/src/stores/scene.ts
index 45b7b0f9b..b2a699d25 100644
--- a/src/stores/scene.ts
+++ b/src/stores/scene.ts
@@ -115,6 +115,29 @@ export const useSceneStore = defineStore('scene', () => {
     selectedIds.value = new Set([id])
   }
 
+  function addToSelection(id: string): void {
+    const obj = objects.value.find((o) => o.id === id)
+    if (!obj || obj.locked) return
+    selectedIds.value = new Set([...selectedIds.value, id])
+  }
+
+  function toggleSelection(id: string): void {
+    const obj = objects.value.find((o) => o.id === id)
+    if (!obj || obj.locked) return
+    const newSet = new Set(selectedIds.value)
+    if (newSet.has(id)) {
+      newSet.delete(id)
+    } else {
+      newSet.add(id)
+    }
+    selectedIds.value = newSet
+  }
+
+  function selectAll(): void {
+    const unlocked = objects.value.filter((o) => !o.locked).map((o) => o.id)
+    selectedIds.value = new Set(unlocked)
+  }
+
   function clearSelection(): void {
     selectedIds.value = new Set()
   }
@@ -143,6 +166,9 @@ export const useSceneStore = defineStore('scene', () => {
     setObjectLocked,
     renameObject,
     select,
+    addToSelection,
+    toggleSelection,
+    selectAll,
     clearSelection,
   }
 })