diff --git a/src/vs/vscode.d.ts b/src/vs/vscode.d.ts
index ccc90b2f95825..15d30bbcb0a70 100644
--- a/src/vs/vscode.d.ts
+++ b/src/vs/vscode.d.ts
@@ -5198,6 +5198,32 @@ declare module 'vscode' {
 		 */
 		export const onDidChangeWorkspaceFolders: Event<WorkspaceFoldersChangeEvent>;
 
+		/**
+		 * Adds workspace folders to the currently opened workspace. Will ignore workspace
+		 * folders that are already part of the workspace.
+		 *
+		 * Note: if this workspace had no folder opened, all extensions will be restarted
+		 * so that the (deprecated) `rootPath` property is updated to point to the first workspace
+		 * folder.
+		 *
+		 * @param folders a list of workspace folders to add.
+		 */
+		export function addWorkspaceFolders(folders: { uri: Uri, name?: string }[]): Thenable<void>;
+
+		/**
+		 * Removes workspace folders from the currently opened workspace if they are part of the
+		 * workspace.
+		 *
+		 * This method will be a no-op when called while not having a workspace opened.
+		 *
+		 * Note: if the first workspace folder is removed, all extensions will be restarted
+		 * so that the (deprecated) `rootPath` property is updated to point to the first workspace
+		 * folder.
+		 *
+		 * @param folders a list of [workspace folders](#WorkspaceFolder) to remove.
+		 */
+		export function removeWorkspaceFolders(folders: WorkspaceFolder[]): Thenable<void>;
+
 		/**
 		 * Returns the [workspace folder](#WorkspaceFolder) that contains a given uri.
 		 * * returns `undefined` when the given uri doesn't match any workspace folder
diff --git a/src/vs/workbench/api/electron-browser/mainThreadWorkspace.ts b/src/vs/workbench/api/electron-browser/mainThreadWorkspace.ts
index 69e0970574381..ccfb7915c192c 100644
--- a/src/vs/workbench/api/electron-browser/mainThreadWorkspace.ts
+++ b/src/vs/workbench/api/electron-browser/mainThreadWorkspace.ts
@@ -52,6 +52,14 @@ export class MainThreadWorkspace implements MainThreadWorkspaceShape {
 		this._proxy.$acceptWorkspaceData(this._contextService.getWorkbenchState() === WorkbenchState.EMPTY ? null : this._contextService.getWorkspace());
 	}
 
+	$addFolders(folders: { uri: URI, name?: string }[]): Thenable<void> {
+		return this._contextService.addFolders(folders);
+	}
+
+	$removeFolders(folders: URI[]): Thenable<void> {
+		return this._contextService.removeFolders(folders);
+	}
+
 	// --- search ---
 
 	$startSearch(include: string | IRelativePattern, exclude: string | IRelativePattern, maxResults: number, requestId: number): Thenable<URI[]> {
diff --git a/src/vs/workbench/api/node/extHost.api.impl.ts b/src/vs/workbench/api/node/extHost.api.impl.ts
index ea70995107947..6f6d3906230e9 100644
--- a/src/vs/workbench/api/node/extHost.api.impl.ts
+++ b/src/vs/workbench/api/node/extHost.api.impl.ts
@@ -397,6 +397,12 @@ export function createApiFactory(
 			get workspaceFolders() {
 				return extHostWorkspace.getWorkspaceFolders();
 			},
+			addWorkspaceFolders(folders) {
+				return extHostWorkspace.addWorkspaceFolders(folders);
+			},
+			removeWorkspaceFolders(folders) {
+				return extHostWorkspace.removeWorkspaceFolders(folders);
+			},
 			onDidChangeWorkspaceFolders: function (listener, thisArgs?, disposables?) {
 				return extHostWorkspace.onDidChangeWorkspace(listener, thisArgs, disposables);
 			},
diff --git a/src/vs/workbench/api/node/extHost.protocol.ts b/src/vs/workbench/api/node/extHost.protocol.ts
index 2e14b41c060b4..9141a5a8770e0 100644
--- a/src/vs/workbench/api/node/extHost.protocol.ts
+++ b/src/vs/workbench/api/node/extHost.protocol.ts
@@ -326,6 +326,8 @@ export interface MainThreadWorkspaceShape extends IDisposable {
 	$startSearch(include: string | IRelativePattern, exclude: string | IRelativePattern, maxResults: number, requestId: number): Thenable<URI[]>;
 	$cancelSearch(requestId: number): Thenable<boolean>;
 	$saveAll(includeUntitled?: boolean): Thenable<boolean>;
+	$addFolders(folders: { uri: URI, name?: string }[]): Thenable<void>;
+	$removeFolders(folders: URI[]): Thenable<void>;
 }
 
 export interface MainThreadFileSystemShape extends IDisposable {
diff --git a/src/vs/workbench/api/node/extHostWorkspace.ts b/src/vs/workbench/api/node/extHostWorkspace.ts
index 654d088c5defe..5da0def7f7d7f 100644
--- a/src/vs/workbench/api/node/extHostWorkspace.ts
+++ b/src/vs/workbench/api/node/extHostWorkspace.ts
@@ -78,6 +78,17 @@ export class ExtHostWorkspace implements ExtHostWorkspaceShape {
 		}
 	}
 
+	addWorkspaceFolders(folders: { uri: URI, name?: string }[]): Thenable<void> {
+		return this._proxy.$addFolders(folders);
+	}
+
+	removeWorkspaceFolders(folders: vscode.WorkspaceFolder[]): Thenable<void> {
+		const existingWorkspaceFolders = this.getWorkspaceFolders();
+		const folderUrisToRemove = folders.filter(folder => existingWorkspaceFolders.indexOf(folder) >= 0).map(f => f.uri);
+
+		return this._proxy.$removeFolders(folderUrisToRemove);
+	}
+
 	getWorkspaceFolder(uri: vscode.Uri, resolveParent?: boolean): vscode.WorkspaceFolder {
 		if (!this._workspace) {
 			return undefined;