diff --git a/src/vs/workbench/api/common/extHost.api.impl.ts b/src/vs/workbench/api/common/extHost.api.impl.ts
index 20331a51a87902d20299ab81206a6699fd5790b3..91868efb3efcb85433799546bb2d1f93eea5b2d1 100644
--- a/src/vs/workbench/api/common/extHost.api.impl.ts
+++ b/src/vs/workbench/api/common/extHost.api.impl.ts
@@ -488,7 +488,8 @@ export function createApiFactoryAndRegisterActors(accessor: ServicesAccessor): I
 				return extHostTerminalService.onDidWriteTerminalData(listener, thisArg, disposables);
 			},
 			getEnvironmentVariableCollection(persistent?: boolean): vscode.EnvironmentVariableCollection {
-				return null!;
+				checkProposedApiEnabled(extension);
+				return extHostTerminalService.getEnvironmentVariableCollection(extension, persistent);
 			},
 			get state() {
 				return extHostWindow.state;
@@ -955,6 +956,7 @@ export function createApiFactoryAndRegisterActors(accessor: ServicesAccessor): I
 			DocumentLink: extHostTypes.DocumentLink,
 			DocumentSymbol: extHostTypes.DocumentSymbol,
 			EndOfLine: extHostTypes.EndOfLine,
+			EnvironmentVariableMutatorType: extHostTypes.EnvironmentVariableMutatorType,
 			EvaluatableExpression: extHostTypes.EvaluatableExpression,
 			EventEmitter: Emitter,
 			ExtensionKind: extHostTypes.ExtensionKind,
diff --git a/src/vs/workbench/api/common/extHostTerminalService.ts b/src/vs/workbench/api/common/extHostTerminalService.ts
index caf46e8a4ced660afe17a47c264d8e0197c69691..b332a4e5cde91f315b49405d01b54d430e1c6aa9 100644
--- a/src/vs/workbench/api/common/extHostTerminalService.ts
+++ b/src/vs/workbench/api/common/extHostTerminalService.ts
@@ -15,6 +15,7 @@ import { IExtHostRpcService } from 'vs/workbench/api/common/extHostRpcService';
 import { TerminalDataBufferer } from 'vs/workbench/contrib/terminal/common/terminalDataBuffering';
 import { IDisposable, DisposableStore } from 'vs/base/common/lifecycle';
 import { Disposable as VSCodeDisposable } from './extHostTypes';
+import { IExtensionDescription } from 'vs/platform/extensions/common/extensions';
 
 export interface IExtHostTerminalService extends ExtHostTerminalServiceShape {
 
@@ -35,7 +36,8 @@ export interface IExtHostTerminalService extends ExtHostTerminalServiceShape {
 	attachPtyToTerminal(id: number, pty: vscode.Pseudoterminal): void;
 	getDefaultShell(useAutomationShell: boolean, configProvider: ExtHostConfigProvider): string;
 	getDefaultShellArgs(useAutomationShell: boolean, configProvider: ExtHostConfigProvider): string[] | string;
-	registerLinkHandler(handler: vscode.TerminalLinkHandler): vscode.Disposable
+	registerLinkHandler(handler: vscode.TerminalLinkHandler): vscode.Disposable;
+	getEnvironmentVariableCollection(extension: IExtensionDescription, persistent?: boolean): vscode.EnvironmentVariableCollection;
 }
 
 export const IExtHostTerminalService = createDecorator<IExtHostTerminalService>('IExtHostTerminalService');
@@ -333,6 +335,7 @@ export abstract class BaseExtHostTerminalService implements IExtHostTerminalServ
 	public abstract $getAvailableShells(): Promise<IShellDefinitionDto[]>;
 	public abstract $getDefaultShellAndArgs(useAutomationShell: boolean): Promise<IShellAndArgsDto>;
 	public abstract $acceptWorkspacePermissionsChanged(isAllowed: boolean): void;
+	public abstract getEnvironmentVariableCollection(extension: IExtensionDescription, persistent?: boolean): vscode.EnvironmentVariableCollection;
 
 	public createExtensionTerminal(options: vscode.ExtensionTerminalOptions): vscode.Terminal {
 		const terminal = new ExtHostTerminal(this._proxy, options, options.name);
@@ -669,4 +672,8 @@ export class WorkerExtHostTerminalService extends BaseExtHostTerminalService {
 	public $acceptWorkspacePermissionsChanged(isAllowed: boolean): void {
 		// No-op for web worker ext host as workspace permissions aren't used
 	}
+
+	public getEnvironmentVariableCollection(extension: IExtensionDescription, persistent?: boolean): vscode.EnvironmentVariableCollection {
+		throw new Error('Not implemented');
+	}
 }
diff --git a/src/vs/workbench/api/common/extHostTypes.ts b/src/vs/workbench/api/common/extHostTypes.ts
index 7ce3ecf2590ac802e14db83e214c6346245f0a12..1c40cf37ffb24c33ea2eb81c65fb89eeac8269d4 100644
--- a/src/vs/workbench/api/common/extHostTypes.ts
+++ b/src/vs/workbench/api/common/extHostTypes.ts
@@ -483,6 +483,12 @@ export enum EndOfLine {
 	CRLF = 2
 }
 
+export enum EnvironmentVariableMutatorType {
+	Replace = 1,
+	Append = 2,
+	Prepend = 3
+}
+
 @es5ClassCompat
 export class TextEdit {
 
diff --git a/src/vs/workbench/api/node/extHostTerminalService.ts b/src/vs/workbench/api/node/extHostTerminalService.ts
index d7809338f8115e859b42d4403dffc010440af1d5..5afd58b47ffaee642415ce67dd015a6719e8449f 100644
--- a/src/vs/workbench/api/node/extHostTerminalService.ts
+++ b/src/vs/workbench/api/node/extHostTerminalService.ts
@@ -22,6 +22,7 @@ import { getSystemShell, detectAvailableShells } from 'vs/workbench/contrib/term
 import { getMainProcessParentEnv } from 'vs/workbench/contrib/terminal/node/terminalEnvironment';
 import { BaseExtHostTerminalService, ExtHostTerminal } from 'vs/workbench/api/common/extHostTerminalService';
 import { IExtHostRpcService } from 'vs/workbench/api/common/extHostRpcService';
+import { IExtensionDescription } from 'vs/platform/extensions/common/extensions';
 
 export class ExtHostTerminalService extends BaseExtHostTerminalService {
 
@@ -215,4 +216,8 @@ export class ExtHostTerminalService extends BaseExtHostTerminalService {
 	public $acceptWorkspacePermissionsChanged(isAllowed: boolean): void {
 		this._isWorkspaceShellAllowed = isAllowed;
 	}
+
+	public getEnvironmentVariableCollection(extension: IExtensionDescription, persistent?: boolean): vscode.EnvironmentVariableCollection {
+		return null!;
+	}
 }