diff --git a/src/vs/workbench/api/node/extHost.api.impl.ts b/src/vs/workbench/api/node/extHost.api.impl.ts
index b5a071701a6b201078ab3b32b409e808fd2b7042..d39add02215b632e63bedbeda4f49af159c527e7 100644
--- a/src/vs/workbench/api/node/extHost.api.impl.ts
+++ b/src/vs/workbench/api/node/extHost.api.impl.ts
@@ -102,7 +102,7 @@ export class ExtHostAPIImplementation {
 		const extHostDocuments = col.define(ExtHostContext.ExtHostDocuments).set<ExtHostDocuments>(new ExtHostDocuments(threadService));
 		const extHostEditors = col.define(ExtHostContext.ExtHostEditors).set<ExtHostEditors>(new ExtHostEditors(threadService, extHostDocuments));
 		const extHostCommands = col.define(ExtHostContext.ExtHostCommands).set<ExtHostCommands>(new ExtHostCommands(threadService, extHostEditors));
-		const extHostConfiguration = col.define(ExtHostContext.ExtHostConfiguration).set<ExtHostConfiguration>(new ExtHostConfiguration());
+		const extHostConfiguration = col.define(ExtHostContext.ExtHostConfiguration).set<ExtHostConfiguration>(new ExtHostConfiguration(threadService));
 		const extHostDiagnostics = col.define(ExtHostContext.ExtHostDiagnostics).set<ExtHostDiagnostics>(new ExtHostDiagnostics(threadService));
 		const languageFeatures = col.define(ExtHostContext.ExtHostLanguageFeatures).set<ExtHostLanguageFeatures>(new ExtHostLanguageFeatures(threadService, extHostDocuments, extHostCommands, extHostDiagnostics));
 		const extHostFileSystemEvent = col.define(ExtHostContext.ExtHostFileSystemEventService).set<ExtHostFileSystemEventService>(new ExtHostFileSystemEventService());
diff --git a/src/vs/workbench/api/node/extHost.contribution.ts b/src/vs/workbench/api/node/extHost.contribution.ts
index bb86e048df38736cfda689f1ef875b5546804948..1399802772f2e3273d8e3b8075f8a00a00a9005a 100644
--- a/src/vs/workbench/api/node/extHost.contribution.ts
+++ b/src/vs/workbench/api/node/extHost.contribution.ts
@@ -61,6 +61,7 @@ export class ExtHostContribution implements IWorkbenchContribution {
 		// Addressable instances
 		const col = new InstanceCollection();
 		col.define(MainContext.MainThreadCommands).set(create(MainThreadCommands));
+		col.define(MainContext.MainThreadConfiguration).set(create(MainThreadConfiguration));
 		col.define(MainContext.MainThreadDiagnostics).set(create(MainThreadDiagnostics));
 		col.define(MainContext.MainThreadDocuments).set(create(MainThreadDocuments));
 		col.define(MainContext.MainThreadEditors).set(create(MainThreadEditors));
diff --git a/src/vs/workbench/api/node/extHost.protocol.ts b/src/vs/workbench/api/node/extHost.protocol.ts
index a7ed16ce7eb8d4724a33ab1805fe87c059f36e09..b93eced9b757d5df9f0e3587e6edfa1d9861c98a 100644
--- a/src/vs/workbench/api/node/extHost.protocol.ts
+++ b/src/vs/workbench/api/node/extHost.protocol.ts
@@ -27,6 +27,8 @@ import * as editorCommon from 'vs/editor/common/editorCommon';
 import * as modes from 'vs/editor/common/modes';
 import {IResourceEdit} from 'vs/editor/common/services/bulkEdit';
 
+import {ConfigurationTarget, ConfigurationEditingResult} from 'vs/workbench/services/configuration/common/configurationEditing';
+
 import {IPickOpenEntry, IPickOptions} from 'vs/workbench/services/quickopen/common/quickOpenService';
 import {IWorkspaceSymbol} from 'vs/workbench/parts/search/common/search';
 import {TextEditorRevealType, ITextEditorConfigurationUpdate, IResolvedTextEditorConfiguration, ISelectionChangeEvent} from './mainThreadEditorsTracker';
@@ -81,6 +83,10 @@ export abstract class MainThreadCommandsShape {
 	$getCommands(): Thenable<string[]> { throw ni(); }
 }
 
+export abstract class MainThreadConfigurationShape {
+	$updateConfigurationOption(target: ConfigurationTarget, key: string, value: any): TPromise<ConfigurationEditingResult> { throw ni(); }
+}
+
 export abstract class MainThreadDiagnosticsShape {
 	$changeMany(owner: string, entries: [URI, IMarkerData[]][]): TPromise<any> { throw ni(); }
 	$clear(owner: string): TPromise<any> { throw ni(); }
@@ -290,6 +296,7 @@ export abstract class ExtHostQuickOpenShape {
 
 export const MainContext = {
 	MainThreadCommands: createMainId<MainThreadCommandsShape>('MainThreadCommands', MainThreadCommandsShape),
+	MainThreadConfiguration: createMainId<MainThreadConfigurationShape>('MainThreadConfiguration', MainThreadConfigurationShape),
 	MainThreadDiagnostics: createMainId<MainThreadDiagnosticsShape>('MainThreadDiagnostics', MainThreadDiagnosticsShape),
 	MainThreadDocuments: createMainId<MainThreadDocumentsShape>('MainThreadDocuments', MainThreadDocumentsShape),
 	MainThreadEditors: createMainId<MainThreadEditorsShape>('MainThreadEditors', MainThreadEditorsShape),
diff --git a/src/vs/workbench/api/node/extHostConfiguration.ts b/src/vs/workbench/api/node/extHostConfiguration.ts
index b37ec21751b8496ee8cb73fc2e9c6ec17f64f797..6bf43202bf4a0ef0e935a950faa821ce494a29a1 100644
--- a/src/vs/workbench/api/node/extHostConfiguration.ts
+++ b/src/vs/workbench/api/node/extHostConfiguration.ts
@@ -8,16 +8,19 @@ import {clone} from 'vs/base/common/objects';
 import {illegalState} from 'vs/base/common/errors';
 import Event, {Emitter} from 'vs/base/common/event';
 import {WorkspaceConfiguration} from 'vscode';
-import {ExtHostConfigurationShape} from './extHost.protocol';
+import {ExtHostConfigurationShape, MainContext, MainThreadConfigurationShape} from './extHost.protocol';
+import {IThreadService} from 'vs/workbench/services/thread/common/threadService';
 
 export class ExtHostConfiguration extends ExtHostConfigurationShape {
 
-	private _config: any;
+	private _proxy: MainThreadConfigurationShape;
 	private _hasConfig: boolean;
+	private _config: any;
 	private _onDidChangeConfiguration: Emitter<void>;
 
-	constructor() {
+	constructor(threadService: IThreadService) {
 		super();
+		this._proxy = threadService.get(MainContext.MainThreadConfiguration);
 		this._onDidChangeConfiguration = new Emitter<void>();
 	}
 
diff --git a/src/vs/workbench/api/node/mainThreadConfiguration.ts b/src/vs/workbench/api/node/mainThreadConfiguration.ts
index 89e9d0ca86f2825d4920d5a20e780aa498a748bf..deab01bda601db3129edb6e8f7f26b659b74bb1f 100644
--- a/src/vs/workbench/api/node/mainThreadConfiguration.ts
+++ b/src/vs/workbench/api/node/mainThreadConfiguration.ts
@@ -4,29 +4,35 @@
  *--------------------------------------------------------------------------------------------*/
 'use strict';
 
+import {TPromise} from 'vs/base/common/winjs.base';
 import {IDisposable, dispose} from 'vs/base/common/lifecycle';
 import {IThreadService} from 'vs/workbench/services/thread/common/threadService';
 import {IWorkbenchConfigurationService} from 'vs/workbench/services/configuration/common/configuration';
-import {ExtHostContext, ExtHostConfigurationShape} from './extHost.protocol';
+import {IConfigurationEditingService, ConfigurationTarget, ConfigurationEditingResult} from 'vs/workbench/services/configuration/common/configurationEditing';
+import {MainThreadConfigurationShape, ExtHostContext} from './extHost.protocol';
 
-export class MainThreadConfiguration {
+export class MainThreadConfiguration extends MainThreadConfigurationShape {
 
-	private _configurationService: IWorkbenchConfigurationService;
+	private _configurationEditingService: IConfigurationEditingService;
 	private _toDispose: IDisposable;
-	private _proxy: ExtHostConfigurationShape;
 
 	constructor(
+		@IConfigurationEditingService configurationEditingService: IConfigurationEditingService,
 		@IWorkbenchConfigurationService configurationService: IWorkbenchConfigurationService,
 		@IThreadService threadService: IThreadService
 	) {
-		this._configurationService = configurationService;
-		this._proxy = threadService.get(ExtHostContext.ExtHostConfiguration);
-
-		this._toDispose = this._configurationService.onDidUpdateConfiguration(event => this._proxy.$acceptConfigurationChanged(event.config));
-		this._proxy.$acceptConfigurationChanged(this._configurationService.getConfiguration());
+		super();
+		this._configurationEditingService = configurationEditingService;
+		const proxy = threadService.get(ExtHostContext.ExtHostConfiguration);
+		this._toDispose = configurationService.onDidUpdateConfiguration(event => proxy.$acceptConfigurationChanged(event.config));
+		proxy.$acceptConfigurationChanged(configurationService.getConfiguration());
 	}
 
 	public dispose(): void {
 		this._toDispose = dispose(this._toDispose);
 	}
+
+	$updateConfigurationOption(target: ConfigurationTarget, key: string, value: any): TPromise<ConfigurationEditingResult> {
+		return this._configurationEditingService.writeConfiguration(target, [{ key, value }]);
+	}
 }