diff --git a/editor/js/Config.js b/editor/js/Config.js
index 620596d1dd62bd..5210b74ff682d3 100644
--- a/editor/js/Config.js
+++ b/editor/js/Config.js
@@ -32,7 +32,8 @@ function Config() {
 		'settings/shortcuts/undo': 'z',
 		'settings/shortcuts/focus': 'f',
 		'settings/shortcuts/perspective': 'p',
-		'settings/shortcuts/orthographic': 'o'
+		'settings/shortcuts/orthographic': 'o',
+		'settings/shortcuts/selectAll': 'a'
 	};
 
 	if ( window.localStorage[ name ] === undefined ) {
diff --git a/editor/js/Selector.js b/editor/js/Selector.js
index b6703b8f1fde6c..d32d079496f45d 100644
--- a/editor/js/Selector.js
+++ b/editor/js/Selector.js
@@ -3,6 +3,12 @@ import * as THREE from 'three';
 const mouse = new THREE.Vector2();
 const raycaster = new THREE.Raycaster();
 
+const _box = new THREE.Box3();
+const _vector = new THREE.Vector3();
+const _deltaMatrix = new THREE.Matrix4();
+const _objectMatrix = new THREE.Matrix4();
+const _parentMatrixInverse = new THREE.Matrix4();
+
 class Selector {
 
 	constructor( editor ) {
@@ -12,9 +18,18 @@ class Selector {
 		this.editor = editor;
 		this.signals = signals;
 
+		this.selection = [];
+
+		// an intermediate group used as pivot when transforming multiple objects
+
+		this.group = new THREE.Group();
+
+		this._groupMatrixWorldInverse = new THREE.Matrix4();
+		this._memberStates = [];
+
 		// signals
 
-		signals.intersectionsDetected.add( ( intersects ) => {
+		signals.intersectionsDetected.add( ( intersects, shiftKey ) => {
 
 			if ( intersects.length > 0 ) {
 
@@ -40,23 +55,53 @@ class Selector {
 
 				}
 
-				// Cycle through objects if the first one is already selected
-
-				const index = objects.indexOf( editor.selected );
+				if ( shiftKey === true && this.selection.length > 0 && editor.selected !== editor.scene && editor.selected !== editor.camera ) {
 
-				if ( index !== - 1 && index < objects.length - 1 ) {
+					// Shift-click toggles membership in the current selection
 
-					this.select( objects[ index + 1 ] );
+					this.toggle( objects[ 0 ] );
 
 				} else {
 
-					this.select( objects[ 0 ] );
+					// Cycle through objects if the first one is already selected
+
+					const index = objects.indexOf( editor.selected );
+
+					if ( index !== - 1 && index < objects.length - 1 ) {
+
+						this.select( objects[ index + 1 ] );
+
+					} else {
+
+						this.select( objects[ 0 ] );
+
+					}
 
 				}
 
 			} else {
 
-				this.select( null );
+				if ( shiftKey !== true ) this.select( null ); // keep the selection when shift-clicking empty space
+
+			}
+
+		} );
+
+		signals.objectChanged.add( ( object ) => {
+
+			if ( this.selection.length < 2 ) return;
+
+			if ( object === this.group ) {
+
+				// the group has been transformed (e.g. via TransformControls), sync its members
+
+				this.applyGroupTransform();
+
+			} else if ( this.selection.indexOf( object ) !== - 1 ) {
+
+				// a member has been changed independently (e.g. via undo/redo), re-anchor the pivot
+
+				this.updateGroup();
 
 			}
 
@@ -94,22 +139,132 @@ class Selector {
 
 	}
 
+	getSelectionBox( target ) {
+
+		target.makeEmpty();
+
+		for ( let i = 0; i < this.selection.length; i ++ ) {
+
+			const object = this.selection[ i ];
+
+			target.expandByObject( object, true );
+			target.expandByPoint( object.getWorldPosition( _vector ) ); // objects without geometry (e.g. lights)
+
+		}
+
+		return target;
+
+	}
+
 	select( object ) {
 
-		if ( this.editor.selected === object ) return;
+		this.setSelection( object === null ? [] : [ object ] );
 
-		let uuid = null;
+	}
 
-		if ( object !== null ) {
+	toggle( object ) {
 
-			uuid = object.uuid;
+		const selection = this.selection.slice();
+
+		const index = selection.indexOf( object );
+
+		if ( index === - 1 ) {
+
+			selection.push( object );
+
+		} else {
+
+			selection.splice( index, 1 );
 
 		}
 
-		this.editor.selected = object;
-		this.editor.config.setKey( 'selected', uuid );
+		this.setSelection( selection );
+
+	}
+
+	setSelection( objects ) {
+
+		const editor = this.editor;
+
+		const hadGroupSelection = this.group.parent !== null;
+
+		this.selection = objects.slice();
 
-		this.signals.objectSelected.dispatch( object );
+		if ( objects.length > 1 ) {
+
+			editor.sceneHelpers.add( this.group );
+			this.updateGroup();
+
+			editor.selected = null;
+			editor.config.setKey( 'selected', null );
+
+			this.signals.objectSelected.dispatch( null );
+
+		} else {
+
+			const object = ( objects.length === 1 ) ? objects[ 0 ] : null;
+
+			editor.sceneHelpers.remove( this.group );
+
+			if ( editor.selected === object && hadGroupSelection === false ) return;
+
+			editor.selected = object;
+			editor.config.setKey( 'selected', ( object !== null ) ? object.uuid : null );
+
+			this.signals.objectSelected.dispatch( object );
+
+		}
+
+	}
+
+	updateGroup() {
+
+		const group = this.group;
+
+		// use the center of the selection's AABB as pivot point
+
+		this.getSelectionBox( _box ).getCenter( group.position );
+		group.quaternion.identity();
+		group.scale.set( 1, 1, 1 );
+		group.updateWorldMatrix();
+
+		this._groupMatrixWorldInverse.copy( group.matrixWorld ).invert();
+
+		// members with a selected ancestor are updated by that ancestor's transform
+
+		const members = this.selection.filter( ( object ) => hasSelectedAncestor( object, this.selection ) === false );
+
+		this._memberStates = members.map( ( object ) => ( { object: object, matrixWorld: object.matrixWorld.clone() } ) );
+
+	}
+
+	applyGroupTransform() {
+
+		const group = this.group;
+
+		group.updateWorldMatrix();
+
+		_deltaMatrix.multiplyMatrices( group.matrixWorld, this._groupMatrixWorldInverse );
+
+		const states = this._memberStates;
+
+		for ( let i = 0; i < states.length; i ++ ) {
+
+			const object = states[ i ].object;
+			const parent = object.parent;
+
+			_objectMatrix.multiplyMatrices( _deltaMatrix, states[ i ].matrixWorld );
+			_parentMatrixInverse.copy( parent.matrixWorld ).invert();
+			_objectMatrix.premultiply( _parentMatrixInverse );
+			_objectMatrix.decompose( object.position, object.quaternion, object.scale );
+
+			object.updateWorldMatrix( false, true );
+
+			const helper = this.editor.helpers[ object.id ];
+
+			if ( helper !== undefined && helper.isSkeletonHelper !== true ) helper.update();
+
+		}
 
 	}
 
@@ -121,4 +276,20 @@ class Selector {
 
 }
 
+function hasSelectedAncestor( object, selection ) {
+
+	let parent = object.parent;
+
+	while ( parent !== null ) {
+
+		if ( selection.indexOf( parent ) !== - 1 ) return true;
+
+		parent = parent.parent;
+
+	}
+
+	return false;
+
+}
+
 export { Selector };
diff --git a/editor/js/Sidebar.Scene.js b/editor/js/Sidebar.Scene.js
index 4d517cab4747d0..deec653b589527 100644
--- a/editor/js/Sidebar.Scene.js
+++ b/editor/js/Sidebar.Scene.js
@@ -131,11 +131,28 @@ function SidebarScene( editor ) {
 
 	const outliner = new UIOutliner( editor );
 	outliner.setId( 'outliner' );
-	outliner.onChange( function () {
+	outliner.onChange( function ( event ) {
+
+		const id = parseInt( outliner.getValue() );
+
+		if ( event.shiftKey === true && editor.selector.selection.length > 0 && editor.selected !== editor.scene && editor.selected !== editor.camera ) {
+
+			const object = ( id === editor.camera.id ) ? editor.camera : editor.scene.getObjectById( id );
+
+			// scene and main camera can't be part of a group selection
+
+			if ( object !== editor.scene && object !== editor.camera ) {
+
+				editor.selector.toggle( object );
+				return;
+
+			}
+
+		}
 
 		ignoreObjectSelectedSignal = true;
 
-		editor.selectById( parseInt( outliner.getValue() ) );
+		editor.selectById( id );
 
 		ignoreObjectSelectedSignal = false;
 
@@ -414,6 +431,18 @@ function SidebarScene( editor ) {
 
 			outliner.setValue( editor.selected.id );
 
+		} else {
+
+			const selection = editor.selector.selection;
+
+			if ( selection.length > 1 ) {
+
+				// restore highlights of a group selection (e.g. after a graph change)
+
+				outliner.setValues( selection.map( ( object ) => object.id ) );
+
+			}
+
 		}
 
 		backgroundType.setValue( editor.backgroundType );
@@ -542,30 +571,57 @@ function SidebarScene( editor ) {
 	} );
 
 
+	function expandAncestors( object ) {
+
+		let needsRefresh = false;
+		let parent = object.parent;
+
+		while ( parent !== editor.scene ) {
+
+			if ( nodeStates.get( parent ) !== true ) {
+
+				nodeStates.set( parent, true );
+				needsRefresh = true;
+
+			}
+
+			parent = parent.parent;
+
+		}
+
+		return needsRefresh;
+
+	}
+
 	signals.objectSelected.add( function ( object ) {
 
 		if ( ignoreObjectSelectedSignal === true ) return;
 
-		if ( object !== null && object.parent !== null ) {
+		const selection = editor.selector.selection;
 
-			let needsRefresh = false;
-			let parent = object.parent;
+		if ( selection.length > 1 ) {
 
-			while ( parent !== editor.scene ) {
+			// highlight all members of a group selection
 
-				if ( nodeStates.get( parent ) !== true ) {
+			let needsRefresh = false;
 
-					nodeStates.set( parent, true );
-					needsRefresh = true;
+			const values = [];
 
-				}
+			for ( let i = 0; i < selection.length; i ++ ) {
 
-				parent = parent.parent;
+				values.push( selection[ i ].id );
+				needsRefresh = expandAncestors( selection[ i ] ) || needsRefresh;
 
 			}
 
 			if ( needsRefresh ) refreshUI();
 
+			outliner.setValues( values );
+
+		} else if ( object !== null && object.parent !== null ) {
+
+			if ( expandAncestors( object ) ) refreshUI();
+
 			outliner.setValue( object.id );
 
 		} else {
diff --git a/editor/js/Sidebar.Settings.Shortcuts.js b/editor/js/Sidebar.Settings.Shortcuts.js
index 20b92a5ba0a513..5e6c37e4407f3d 100644
--- a/editor/js/Sidebar.Settings.Shortcuts.js
+++ b/editor/js/Sidebar.Settings.Shortcuts.js
@@ -24,7 +24,7 @@ function SidebarSettingsShortcuts( editor ) {
 	headerRow.add( new UIText( strings.getKey( 'sidebar/settings/shortcuts' ).toUpperCase() ) );
 	container.add( headerRow );
 
-	const shortcuts = [ 'translate', 'rotate', 'scale', 'undo', 'focus', 'perspective', 'orthographic' ];
+	const shortcuts = [ 'translate', 'rotate', 'scale', 'undo', 'focus', 'perspective', 'orthographic', 'selectAll' ];
 
 	function createShortcutInput( name ) {
 
@@ -106,27 +106,81 @@ function SidebarSettingsShortcuts( editor ) {
 
 				// fall-through
 
-			case 'delete':
+			case 'delete': {
 
-				const object = editor.selected;
+				const objects = editor.selector.selection;
 
-				if ( object === null || object.parent === null ) return;
+				const commands = [];
 
-				if ( object.isSpotLight || object.isDirectionalLight ) {
+				for ( let i = 0; i < objects.length; i ++ ) {
 
-					editor.execute( new MultiCmdsCommand( editor, [
-						new RemoveObjectCommand( editor, object ),
-						new RemoveObjectCommand( editor, object.target )
-					] ) );
+					const object = objects[ i ];
+
+					if ( object.parent === null ) continue; // avoid deleting the camera or scene
+
+					if ( object.isSpotLight || object.isDirectionalLight ) {
+
+						commands.push( new RemoveObjectCommand( editor, object ) );
+						commands.push( new RemoveObjectCommand( editor, object.target ) );
+
+					} else {
+
+						commands.push( new RemoveObjectCommand( editor, object ) );
+
+					}
+
+				}
+
+				if ( commands.length === 1 ) {
+
+					editor.execute( commands[ 0 ] );
+
+				} else if ( commands.length > 1 ) {
+
+					editor.execute( new MultiCmdsCommand( editor, commands ) );
+
+				}
+
+				break;
+
+			}
+
+			case config.getKey( 'settings/shortcuts/selectAll' ): {
+
+				if ( event.altKey === true || event.ctrlKey === true || event.metaKey === true ) break;
+
+				// toggle between selecting and deselecting all scene objects
+
+				const objects = editor.scene.children;
+				const selection = editor.selector.selection;
+
+				let allSelected = objects.length > 0;
+
+				for ( let i = 0; i < objects.length; i ++ ) {
+
+					if ( selection.indexOf( objects[ i ] ) === - 1 ) {
+
+						allSelected = false;
+						break;
+
+					}
+
+				}
+
+				if ( allSelected === true ) {
+
+					editor.deselect();
 
 				} else {
 
-					editor.execute( new RemoveObjectCommand( editor, object ) );
+					editor.selector.setSelection( objects );
 
 				}
 
 				break;
 
+			}
+
 			case config.getKey( 'settings/shortcuts/translate' ):
 
 				signals.transformModeChanged.dispatch( 'translate' );
diff --git a/editor/js/Strings.js b/editor/js/Strings.js
index 7627143f21731a..cc429b3c599dd8 100644
--- a/editor/js/Strings.js
+++ b/editor/js/Strings.js
@@ -400,6 +400,7 @@ function Strings( config ) {
 			'sidebar/settings/shortcuts/scale': 'مقیاس',
 			'sidebar/settings/shortcuts/undo': 'بازگشت به عقب',
 			'sidebar/settings/shortcuts/focus': 'فوکوس',
+			'sidebar/settings/shortcuts/selectAll': 'انتخاب همه',
 
 			'sidebar/history': 'هیستوری',
 			'sidebar/history/clear': 'پاک کردن',
@@ -852,6 +853,7 @@ function Strings( config ) {
 			'sidebar/settings/shortcuts/focus': 'Focus',
 			'sidebar/settings/shortcuts/perspective': 'Perspective',
 			'sidebar/settings/shortcuts/orthographic': 'Orthographic',
+			'sidebar/settings/shortcuts/selectAll': 'Select All',
 
 			'sidebar/history': 'History',
 			'sidebar/history/clear': 'Clear',
@@ -1302,6 +1304,7 @@ function Strings( config ) {
 			'sidebar/settings/shortcuts/scale': 'Échelle',
 			'sidebar/settings/shortcuts/undo': 'Annuler',
 			'sidebar/settings/shortcuts/focus': 'Focus',
+			'sidebar/settings/shortcuts/selectAll': 'Tout sélectionner',
 
 			'sidebar/history': 'Historique',
 			'sidebar/history/clear': 'Supprimer',
@@ -1752,6 +1755,7 @@ function Strings( config ) {
 			'sidebar/settings/shortcuts/scale': '缩放',
 			'sidebar/settings/shortcuts/undo': '撤销',
 			'sidebar/settings/shortcuts/focus': '聚焦',
+			'sidebar/settings/shortcuts/selectAll': '全选',
 
 			'sidebar/history': '历史记录',
 			'sidebar/history/clear': '清空',
@@ -2202,6 +2206,7 @@ function Strings( config ) {
 			'sidebar/settings/shortcuts/scale': 'スケール',
 			'sidebar/settings/shortcuts/undo': '元に戻す',
 			'sidebar/settings/shortcuts/focus': 'フォーカス',
+			'sidebar/settings/shortcuts/selectAll': 'すべて選択',
 
 			'sidebar/history': '履歴',
 			'sidebar/history/clear': 'クリア',
@@ -2651,6 +2656,7 @@ function Strings( config ) {
 			'sidebar/settings/shortcuts/scale': '스케일',
 			'sidebar/settings/shortcuts/undo': '되돌리기',
 			'sidebar/settings/shortcuts/focus': '포커스',
+			'sidebar/settings/shortcuts/selectAll': '모두 선택',
 
 			'sidebar/history': '기록',
 			'sidebar/history/clear': '지우기',
diff --git a/editor/js/Viewport.js b/editor/js/Viewport.js
index f399da7235bf74..2a9027f0d3e95a 100644
--- a/editor/js/Viewport.js
+++ b/editor/js/Viewport.js
@@ -16,6 +16,7 @@ import { XR } from './Viewport.XR.js';
 import { SetPositionCommand } from './commands/SetPositionCommand.js';
 import { SetRotationCommand } from './commands/SetRotationCommand.js';
 import { SetScaleCommand } from './commands/SetScaleCommand.js';
+import { MultiCmdsCommand } from './commands/MultiCmdsCommand.js';
 
 import { ColorEnvironment } from 'three/addons/environments/ColorEnvironment.js';
 import { RoomEnvironment } from 'three/addons/environments/RoomEnvironment.js';
@@ -72,9 +73,7 @@ function Viewport( editor ) {
 	selectionBox.visible = false;
 	sceneHelpers.add( selectionBox );
 
-	let objectPositionOnDown = null;
-	let objectRotationOnDown = null;
-	let objectScaleOnDown = null;
+	let objectStatesOnDown = [];
 
 	const transformControls = new TransformControls( camera );
 	transformControls.addEventListener( 'axis-changed', function () {
@@ -91,50 +90,56 @@ function Viewport( editor ) {
 
 		const object = transformControls.object;
 
-		objectPositionOnDown = object.position.clone();
-		objectRotationOnDown = object.rotation.clone();
-		objectScaleOnDown = object.scale.clone();
+		const objects = ( object === selector.group ) ? selector.selection : [ object ];
+
+		objectStatesOnDown = objects.map( ( object ) => ( {
+			object: object,
+			position: object.position.clone(),
+			rotation: object.rotation.clone(),
+			scale: object.scale.clone()
+		} ) );
 
 		controls.enabled = false;
 
 	} );
 	transformControls.addEventListener( 'mouseUp', function () {
 
-		const object = transformControls.object;
+		if ( transformControls.object !== undefined ) {
 
-		if ( object !== undefined ) {
+			const commands = [];
 
-			switch ( transformControls.getMode() ) {
+			for ( let i = 0; i < objectStatesOnDown.length; i ++ ) {
 
-				case 'translate':
+				const state = objectStatesOnDown[ i ];
+				const object = state.object;
 
-					if ( ! objectPositionOnDown.equals( object.position ) ) {
+				if ( ! state.position.equals( object.position ) ) {
 
-						editor.execute( new SetPositionCommand( editor, object, object.position, objectPositionOnDown ) );
+					commands.push( new SetPositionCommand( editor, object, object.position, state.position ) );
 
-					}
+				}
 
-					break;
+				if ( ! state.rotation.equals( object.rotation ) ) {
 
-				case 'rotate':
+					commands.push( new SetRotationCommand( editor, object, object.rotation, state.rotation ) );
 
-					if ( ! objectRotationOnDown.equals( object.rotation ) ) {
+				}
 
-						editor.execute( new SetRotationCommand( editor, object, object.rotation, objectRotationOnDown ) );
+				if ( ! state.scale.equals( object.scale ) ) {
 
-					}
+					commands.push( new SetScaleCommand( editor, object, object.scale, state.scale ) );
 
-					break;
+				}
 
-				case 'scale':
+			}
 
-					if ( ! objectScaleOnDown.equals( object.scale ) ) {
+			if ( commands.length === 1 ) {
 
-						editor.execute( new SetScaleCommand( editor, object, object.scale, objectScaleOnDown ) );
+				editor.execute( commands[ 0 ] );
 
-					}
+			} else if ( commands.length > 1 ) {
 
-					break;
+				editor.execute( new MultiCmdsCommand( editor, commands ) );
 
 			}
 
@@ -193,12 +198,12 @@ function Viewport( editor ) {
 
 	}
 
-	function handleClick() {
+	function handleClick( event ) {
 
 		if ( onDownPosition.distanceTo( onUpPosition ) === 0 ) {
 
 			const intersects = selector.getPointerIntersects( onUpPosition, camera );
-			signals.intersectionsDetected.dispatch( intersects );
+			signals.intersectionsDetected.dispatch( intersects, event.shiftKey );
 
 			render();
 
@@ -224,7 +229,7 @@ function Viewport( editor ) {
 		const array = getMousePosition( container.dom, event.clientX, event.clientY );
 		onUpPosition.fromArray( array );
 
-		handleClick();
+		handleClick( event );
 
 		document.removeEventListener( 'mouseup', onMouseUp );
 
@@ -248,7 +253,7 @@ function Viewport( editor ) {
 		const array = getMousePosition( container.dom, touch.clientX, touch.clientY );
 		onUpPosition.fromArray( array );
 
-		handleClick();
+		handleClick( event );
 
 		document.removeEventListener( 'touchend', onTouchEnd );
 
@@ -441,7 +446,14 @@ function Viewport( editor ) {
 		selectionBox.visible = false;
 		transformControls.detach();
 
-		if ( object !== null && object !== scene && object !== camera ) {
+		if ( selector.selection.length > 1 ) {
+
+			selector.getSelectionBox( box );
+
+			selectionBox.visible = true;
+			transformControls.attach( selector.group );
+
+		} else if ( object !== null && object !== scene && object !== camera ) {
 
 			box.setFromObject( object, true );
 
@@ -484,6 +496,10 @@ function Viewport( editor ) {
 
 			box.setFromObject( object, true );
 
+		} else if ( selector.selection.length > 1 && ( object === selector.group || selector.selection.indexOf( object ) !== - 1 ) ) {
+
+			selector.getSelectionBox( box );
+
 		}
 
 		if ( object.isPerspectiveCamera ) {
diff --git a/editor/js/libs/ui.three.js b/editor/js/libs/ui.three.js
index 0ac5490810715c..8d84c7007eb237 100644
--- a/editor/js/libs/ui.three.js
+++ b/editor/js/libs/ui.three.js
@@ -349,11 +349,12 @@ class UIOutliner extends UIDiv {
 
 		}
 
-		function onClick() {
+		function onClick( event ) {
 
 			scope.setValue( this.value );
 
 			const changeEvent = new Event( 'change', { bubbles: true, cancelable: true } );
+			changeEvent.shiftKey = event.shiftKey;
 			scope.dom.dispatchEvent( changeEvent );
 
 		}
@@ -551,6 +552,31 @@ class UIOutliner extends UIDiv {
 
 	}
 
+	setValues( values ) {
+
+		for ( let i = 0; i < this.options.length; i ++ ) {
+
+			const element = this.options[ i ];
+
+			if ( values.indexOf( element.value ) !== - 1 ) {
+
+				element.classList.add( 'active' );
+
+			} else {
+
+				element.classList.remove( 'active' );
+
+			}
+
+		}
+
+		this.selectedIndex = - 1;
+		this.selectedValue = null;
+
+		return this;
+
+	}
+
 }
 
 class UIPoints extends UISpan {