diff --git a/src/vs/vscode.d.ts b/src/vs/vscode.d.ts
index 97e1ac32a48..2f4b56a8a87 100644
--- a/src/vs/vscode.d.ts
+++ b/src/vs/vscode.d.ts
@@ -1350,12 +1350,14 @@ declare module 'vscode' {
 
 	export interface TreeContentProvider {
 		provideTreeContent(): Thenable<ITreeNode>;
+		resolveChildren(node: ITreeNode): Thenable<ITreeNode[]>;
 	}
 
 	export interface ITreeNode {
 		label: string;
 		isExpanded: boolean;
-		children: ITreeNode[]
+		children: ITreeNode[];
+		isChildrenResolved: boolean;
 	}
 
 	/**
diff --git a/src/vs/workbench/api/node/extHost.protocol.ts b/src/vs/workbench/api/node/extHost.protocol.ts
index 43ab9e5fbd2..f84739f296f 100644
--- a/src/vs/workbench/api/node/extHost.protocol.ts
+++ b/src/vs/workbench/api/node/extHost.protocol.ts
@@ -264,6 +264,7 @@ export abstract class ExtHostEditorsShape {
 
 export abstract class ExtHostExplorersShape {
 	$provideTreeContent(treeContentProviderId: string): TPromise<string> { throw ni(); };
+	$resolveChildren(treeContentProviderId: string, node: vscode.ITreeNode): TPromise<string> { throw ni(); }
 }
 
 export abstract class ExtHostExtensionServiceShape {
diff --git a/src/vs/workbench/api/node/extHostExplorers.ts b/src/vs/workbench/api/node/extHostExplorers.ts
index f0be05d4693..4cdd46858d6 100644
--- a/src/vs/workbench/api/node/extHostExplorers.ts
+++ b/src/vs/workbench/api/node/extHostExplorers.ts
@@ -46,4 +46,15 @@ export class ExtHostExplorers extends ExtHostExplorersShape {
 			return JSON.stringify(treeContent);
 		}));
 	}
+
+	$resolveChildren(treeContentProviderId: string, node: vscode.ITreeNode): TPromise<string> {
+		const provider = this._treeContentProviders[treeContentProviderId];
+		if (!provider) {
+			throw new Error(`no TreeContentProvider registered with id '${treeContentProviderId}'`);
+		}
+
+		return TPromise.wrap(provider.resolveChildren(node).then(children => {
+			return JSON.stringify(children);
+		}));
+	}
 }
diff --git a/src/vs/workbench/api/node/mainThreadExplorers.ts b/src/vs/workbench/api/node/mainThreadExplorers.ts
index 3e31c82261e..04e0c080600 100644
--- a/src/vs/workbench/api/node/mainThreadExplorers.ts
+++ b/src/vs/workbench/api/node/mainThreadExplorers.ts
@@ -28,6 +28,11 @@ export class MainThreadExplorers extends MainThreadExplorersShape {
 				return this._proxy.$provideTreeContent(providerId).then(jsonTree => {
 					return <ITreeNode>JSON.parse(jsonTree);
 				})
+			},
+			resolveChildren: (node: ITreeNode): TPromise<ITreeNode[]> => {
+				return this._proxy.$resolveChildren(providerId, node).then(jsonChildren => {
+					return <ITreeNode[]>JSON.parse(jsonChildren);
+				})
 			}
 		});
 	}
diff --git a/src/vs/workbench/parts/explorers/browser/treeExplorerViewletService.ts b/src/vs/workbench/parts/explorers/browser/treeExplorerViewletService.ts
index f899fc22680..b9171622480 100644
--- a/src/vs/workbench/parts/explorers/browser/treeExplorerViewletService.ts
+++ b/src/vs/workbench/parts/explorers/browser/treeExplorerViewletService.ts
@@ -4,7 +4,6 @@ import { ITreeNode, TreeContentProvider } from 'vscode';
 import { TPromise } from 'vs/base/common/winjs.base';
 import Event, {Emitter} from 'vs/base/common/event';
 import { IInstantiationService, createDecorator } from 'vs/platform/instantiation/common/instantiation';
-import { TreeViewNode } from 'vs/workbench/parts/explorers/common/treeViewModel';
 
 export const ITreeExplorerViewletService = createDecorator<ITreeExplorerViewletService>('customViewletService');
 
@@ -13,6 +12,7 @@ export interface ITreeExplorerViewletService {
 
 	registerTreeContentProvider(providerId: string, provider: TreeContentProvider): void;
 	provideTreeContent(providerId: string): TPromise<ITreeNode>;
+	resolveChildren(providerId: string, node: ITreeNode): TPromise<ITreeNode[]>;
 }
 
 export class TreeExplorerViewletService implements ITreeExplorerViewletService {
@@ -21,7 +21,7 @@ export class TreeExplorerViewletService implements ITreeExplorerViewletService {
 	private _treeContentProviders: { [providerId: string]: TreeContentProvider; };
 
 	constructor(
-		@IInstantiationService private _instantiationService: IInstantiationService,
+		@IInstantiationService private _instantiationService: IInstantiationService
 	) {
 		this._treeContentProviders = Object.create(null);
 	}
@@ -33,4 +33,8 @@ export class TreeExplorerViewletService implements ITreeExplorerViewletService {
 	provideTreeContent(providerId: string): TPromise<ITreeNode> {
 		return TPromise.wrap(this._treeContentProviders[providerId].provideTreeContent());
 	}
+
+	resolveChildren(providerId: string, node: ITreeNode): TPromise<ITreeNode[]> {
+		return TPromise.wrap(this._treeContentProviders[providerId].resolveChildren(node));
+	}
 }
diff --git a/src/vs/workbench/parts/explorers/browser/views/treeViewer.ts b/src/vs/workbench/parts/explorers/browser/views/treeViewer.ts
index 0ba9f357861..69634812c3a 100644
--- a/src/vs/workbench/parts/explorers/browser/views/treeViewer.ts
+++ b/src/vs/workbench/parts/explorers/browser/views/treeViewer.ts
@@ -14,23 +14,41 @@ import { ContributableActionProvider } from 'vs/workbench/browser/actionBarRegis
 import { IContextViewService, IContextMenuService } from 'vs/platform/contextview/browser/contextView';
 import { IExtensionService } from 'vs/platform/extensions/common/extensions';
 import { IModeService } from 'vs/editor/common/services/modeService';
+import { ITreeExplorerViewletService } from 'vs/workbench/parts/explorers/browser/treeExplorerViewletService';
+
+const providerId = 'pineTree';
 
 export class TreeDataSource implements IDataSource {
-
-	constructor() {
+	constructor(
+		@ITreeExplorerViewletService private treeExplorerViewletService: ITreeExplorerViewletService
+	) {
 
 	}
 
-	public getId(tree: ITree, node: TreeViewNode): string {
+	public getId(tree: ITree, node: vscode.ITreeNode): string {
 		return node.label;
 	}
 
-	public hasChildren(tree: ITree, node: TreeViewNode): boolean {
-		return node.children && node.children.length > 0;
+	public hasChildren(tree: ITree, node: vscode.ITreeNode): boolean {
+		if (node.isChildrenResolved) {
+			return node.children && node.children.length > 0;
+		} else {
+			return true;
+		}
 	}
 
-	public getChildren(tree: ITree, node: TreeViewNode): TPromise<TreeViewNode[]> {
-		return TPromise.as(node.children);
+	public getChildren(tree: ITree, node: vscode.ITreeNode): TPromise<vscode.ITreeNode[]> {
+		if (node.isChildrenResolved) {
+			return TPromise.as(node.children);
+		} else {
+			return this.treeExplorerViewletService.resolveChildren(providerId, node).then(children => {
+				children.forEach(child => {
+					node.children.push(child);
+				});
+				node.isChildrenResolved = true;
+				return node.children;
+			});
+		}
 	}
 
 	public getParent(tree: ITree, node: TreeViewNode): TPromise<TreeViewNode> {
@@ -79,7 +97,7 @@ export class TreeController extends DefaultController {
 		super.onLeftClick(tree, node, event, origin);
 
 		console.log(node.label);
-	
+
 		return true;
 	}
 }
diff --git a/src/vs/workbench/parts/explorers/common/treeViewModel.ts b/src/vs/workbench/parts/explorers/common/treeViewModel.ts
index 540a57a395f..0457c25afcd 100644
--- a/src/vs/workbench/parts/explorers/common/treeViewModel.ts
+++ b/src/vs/workbench/parts/explorers/common/treeViewModel.ts
@@ -4,7 +4,8 @@ export class TreeViewNode implements vscode.ITreeNode {
     public label: string,
     public isExpanded: boolean = true,
     public parent: TreeViewNode = null,
-    public children: TreeViewNode[] = []) {
+    public children: TreeViewNode[] = [],
+    public isChildrenResolved: boolean = true) {
   }
 
   addChild(child: TreeViewNode) {