diff --git a/src/vs/platform/extensionManagement/common/extensionManagement.ts b/src/vs/platform/extensionManagement/common/extensionManagement.ts
index b5f62c98da6940123b62cd0f570e158d275d6f1e..cf442e6c925dee22d5fb0e1fd109ddfb60bd2945 100644
--- a/src/vs/platform/extensionManagement/common/extensionManagement.ts
+++ b/src/vs/platform/extensionManagement/common/extensionManagement.ts
@@ -12,6 +12,8 @@ import { IPager } from 'vs/base/common/paging';
 import { createDecorator } from 'vs/platform/instantiation/common/instantiation';
 import { IRequestContext } from 'vs/base/node/request';
 
+export const EXTENSION_IDENTIFIER_PATTERN = '^[a-z0-9A-Z][a-z0-9\-A-Z]*\\.[a-z0-9A-Z][a-z0-9\-A-Z]*$';
+
 export interface ICommand {
 	command: string;
 	title: string;
diff --git a/src/vs/platform/extensionManagement/test/common/extensionManagement.test.ts b/src/vs/platform/extensionManagement/test/common/extensionManagement.test.ts
new file mode 100644
index 0000000000000000000000000000000000000000..75794b5171bb92fd2b478de01234f47b4ab0cc91
--- /dev/null
+++ b/src/vs/platform/extensionManagement/test/common/extensionManagement.test.ts
@@ -0,0 +1,29 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+'use strict';
+
+import * as assert from 'assert';
+import {EXTENSION_IDENTIFIER_PATTERN} from 'vs/platform/extensionManagement/common/extensionManagement';
+
+suite('Extension Identifier Pattern', () => {
+
+	test('extension identifier pattern', () => {
+		var regEx = new RegExp(EXTENSION_IDENTIFIER_PATTERN);
+		assert.equal(true, regEx.test('publisher.name'));
+		assert.equal(true, regEx.test('publiSher.name'));
+		assert.equal(true, regEx.test('publisher.Name'));
+		assert.equal(true, regEx.test('PUBLISHER.NAME'));
+		assert.equal(true, regEx.test('PUBLISHEr.NAMe'));
+		assert.equal(true, regEx.test('PUBLISHEr.N-AMe'));
+		assert.equal(true, regEx.test('PUBLISH12Er90.N-A54Me123'));
+		assert.equal(true, regEx.test('111PUBLISH12Er90.N-1111A54Me123'));
+		assert.equal(false, regEx.test('publishername'));
+		assert.equal(false, regEx.test('-publisher.name'));
+		assert.equal(false, regEx.test('publisher.-name'));
+		assert.equal(false, regEx.test('-publisher.-name'));
+		assert.equal(false, regEx.test('publ_isher.name'));
+		assert.equal(false, regEx.test('publisher._name'));
+	});
+});
\ No newline at end of file
diff --git a/src/vs/workbench/parts/extensions/electron-browser/extensionTipsService.ts b/src/vs/workbench/parts/extensions/electron-browser/extensionTipsService.ts
index 87d31a4e598f24c20a670c2e6430aa389bbdc1fa..6dc6589d68ee07764c74d1c0dc85a986c55c9abd 100644
--- a/src/vs/workbench/parts/extensions/electron-browser/extensionTipsService.ts
+++ b/src/vs/workbench/parts/extensions/electron-browser/extensionTipsService.ts
@@ -7,7 +7,7 @@ import { localize } from 'vs/nls';
 import {forEach} from 'vs/base/common/collections';
 import {IDisposable, dispose} from 'vs/base/common/lifecycle';
 import {match} from 'vs/base/common/glob';
-import {IExtensionManagementService, IExtensionGalleryService, IExtensionTipsService, LocalExtensionType} from 'vs/platform/extensionManagement/common/extensionManagement';
+import {IExtensionManagementService, IExtensionGalleryService, IExtensionTipsService, LocalExtensionType, EXTENSION_IDENTIFIER_PATTERN} from 'vs/platform/extensionManagement/common/extensionManagement';
 import { IExtensionsConfiguration, ConfigurationKey } from './extensions';
 import {IModelService} from 'vs/editor/common/services/modelService';
 import {IModel} from 'vs/editor/common/editorCommon';
@@ -49,6 +49,10 @@ export class ExtensionTipsService implements IExtensionTipsService {
 
 	getWorkspaceRecommendations(): string[] {
 		const configuration = this.configurationService.getConfiguration<IExtensionsConfiguration>(ConfigurationKey);
+		if (configuration.recommendations) {
+			const regEx = new RegExp(EXTENSION_IDENTIFIER_PATTERN);
+			return configuration.recommendations.filter(recommendation => regEx.test(recommendation));
+		}
 		return configuration.recommendations || [];
 	}
 
diff --git a/src/vs/workbench/parts/extensions/electron-browser/extensionsFileTemplate.ts b/src/vs/workbench/parts/extensions/electron-browser/extensionsFileTemplate.ts
index eb6520b8e699a9c706cce9f23f3978db6f939469..6588bff30cad48c2e25b988baf5ae459a85526b5 100644
--- a/src/vs/workbench/parts/extensions/electron-browser/extensionsFileTemplate.ts
+++ b/src/vs/workbench/parts/extensions/electron-browser/extensionsFileTemplate.ts
@@ -5,6 +5,7 @@
 
 import { localize } from 'vs/nls';
 import { IJSONSchema } from 'vs/base/common/jsonSchema';
+import { EXTENSION_IDENTIFIER_PATTERN } from 'vs/platform/extensionManagement/common/extensionManagement';
 
 export const SchemaId = 'vscode://schemas/extensions';
 export const Schema: IJSONSchema = {
@@ -14,10 +15,12 @@ export const Schema: IJSONSchema = {
 	properties: {
 		recommendations: {
 			type: 'array',
-			description: localize('app.extensions.json.recommendations', "List of extensions recommendations. The identifier of an extension is always ${publisher}.${name}. For example: vscode.csharp."),
+			description: localize('app.extensions.json.recommendations', "List of extensions recommendations. The identifier of an extension is always '${publisher}.${name}'. For example: 'vscode.csharp'."),
 			items: {
 				type: 'string',
 				defaultSnippets: [{ label: 'Example', body: 'vscode.csharp' }],
+				pattern: EXTENSION_IDENTIFIER_PATTERN,
+				errorMessage: localize('app.extension.identifier.errorMessage', "Expected format '${publisher}.${name}'. Example: 'vscode.csharp'.")
 			},
 		},
 	}