diff --git a/modules/angular2/src/core/change_detection/codegen_name_util.ts b/modules/angular2/src/core/change_detection/codegen_name_util.ts
index ac852a7684..a797e973a3 100644
--- a/modules/angular2/src/core/change_detection/codegen_name_util.ts
+++ b/modules/angular2/src/core/change_detection/codegen_name_util.ts
@@ -109,8 +109,8 @@ export class CodegenNameUtil {
       }
     }
     var assignmentsCode =
-        ListWrapper.isEmpty(assignments) ? '' : `${ListWrapper.join(assignments, '=')} = false;`;
-    return `var ${ListWrapper.join(declarations, ',')};${assignmentsCode}`;
+        ListWrapper.isEmpty(assignments) ? '' : `${assignments.join('=')} = false;`;
+    return `var ${declarations.join(',')};${assignmentsCode}`;
   }
 
   /**
@@ -169,20 +169,16 @@ export class CodegenNameUtil {
 
     // At least one assignment.
     fields.push(`${this._utilName}.uninitialized;`);
-    return ListWrapper.join(fields, ' = ');
+    return fields.join(' = ');
   }
 
   /**
    * Generates statements destroying all pipe variables.
    */
   genPipeOnDestroy(): string {
-    return ListWrapper.join(
-        ListWrapper.map(
-            ListWrapper.filter(this._records, (r) => { return r.isPipeRecord(); }),
-            (r) => {
-              return `${this._utilName}.callPipeOnDestroy(${this.getPipeName(r.selfIndex)});`;
-            }),
-        '\n');
+    return ListWrapper.filter(this._records, (r) => { return r.isPipeRecord(); })
+        .map(r => `${this._utilName}.callPipeOnDestroy(${this.getPipeName(r.selfIndex)});`)
+        .join('\n');
   }
 
   getPipeName(idx: number): string {
diff --git a/modules/angular2/src/core/change_detection/proto_change_detector.ts b/modules/angular2/src/core/change_detection/proto_change_detector.ts
index 9ead718fc5..fdc45213d5 100644
--- a/modules/angular2/src/core/change_detection/proto_change_detector.ts
+++ b/modules/angular2/src/core/change_detection/proto_change_detector.ts
@@ -314,8 +314,7 @@ function _arrayFn(length: number): Function {
 }
 
 function _mapPrimitiveName(keys: any[]) {
-  var stringifiedKeys =
-      ListWrapper.join(ListWrapper.map(keys, (k) => isString(k) ? `"${k}"` : `${k}`), ", ");
+  var stringifiedKeys = keys.map(k => isString(k) ? `"${k}"` : `${k}`).join(', ');
   return `mapFn([${stringifiedKeys}])`;
 }
 
diff --git a/modules/angular2/src/core/compiler/xhr_mock.ts b/modules/angular2/src/core/compiler/xhr_mock.ts
index 33d1ac9f09..dd67bc19a8 100644
--- a/modules/angular2/src/core/compiler/xhr_mock.ts
+++ b/modules/angular2/src/core/compiler/xhr_mock.ts
@@ -5,15 +5,9 @@ import {BaseException, WrappedException} from 'angular2/src/core/facade/exceptio
 import {PromiseCompleter, PromiseWrapper, Promise} from 'angular2/src/core/facade/async';
 
 export class MockXHR extends XHR {
-  private _expectations: _Expectation[];
+  private _expectations: _Expectation[] = [];
   private _definitions = new Map<string, string>();
-  private _requests: _PendingRequest[];
-
-  constructor() {
-    super();
-    this._expectations = [];
-    this._requests = [];
-  }
+  private _requests: _PendingRequest[] = [];
 
   get(url: string): Promise<string> {
     var request = new _PendingRequest(url);
@@ -50,7 +44,7 @@ export class MockXHR extends XHR {
       urls.push(expectation.url);
     }
 
-    throw new BaseException(`Unsatisfied requests: ${ListWrapper.join(urls, ', ')}`);
+    throw new BaseException(`Unsatisfied requests: ${urls.join(', ')}`);
   }
 
   private _processRequest(request: _PendingRequest) {
diff --git a/modules/angular2/src/core/debug/debug_element_view_listener.ts b/modules/angular2/src/core/debug/debug_element_view_listener.ts
index 42ed16944d..c520cadc1f 100644
--- a/modules/angular2/src/core/debug/debug_element_view_listener.ts
+++ b/modules/angular2/src/core/debug/debug_element_view_listener.ts
@@ -20,7 +20,7 @@ var _nextId = 0;
 
 function _setElementId(element, indices: number[]) {
   if (isPresent(element)) {
-    DOM.setData(element, NG_ID_PROPERTY, ListWrapper.join(indices, NG_ID_SEPARATOR));
+    DOM.setData(element, NG_ID_PROPERTY, indices.join(NG_ID_SEPARATOR));
   }
 }
 
diff --git a/modules/angular2/src/core/dom/parse5_adapter.ts b/modules/angular2/src/core/dom/parse5_adapter.ts
index 09df09e961..57e1e2e5c0 100644
--- a/modules/angular2/src/core/dom/parse5_adapter.ts
+++ b/modules/angular2/src/core/dom/parse5_adapter.ts
@@ -356,7 +356,7 @@ export class Parse5DomAdapter extends DomAdapter {
     var index = classList.indexOf(classname);
     if (index == -1) {
       classList.push(classname);
-      element.attribs["class"] = element.className = ListWrapper.join(classList, " ");
+      element.attribs["class"] = element.className = classList.join(" ");
     }
   }
   removeClass(element, classname: string) {
@@ -364,7 +364,7 @@ export class Parse5DomAdapter extends DomAdapter {
     var index = classList.indexOf(classname);
     if (index > -1) {
       classList.splice(index, 1);
-      element.attribs["class"] = element.className = ListWrapper.join(classList, " ");
+      element.attribs["class"] = element.className = classList.join(" ");
     }
   }
   hasClass(element, classname: string): boolean {
diff --git a/modules/angular2/src/core/facade/collection.dart b/modules/angular2/src/core/facade/collection.dart
index 9f566806bf..af6ddea0d6 100644
--- a/modules/angular2/src/core/facade/collection.dart
+++ b/modules/angular2/src/core/facade/collection.dart
@@ -167,7 +167,6 @@ class ListWrapper {
     l.clear();
   }
 
-  static String join(List l, String s) => l.join(s);
   static bool isEmpty(Iterable list) => list.isEmpty;
   static void fill(List l, value, [int start = 0, int end]) {
     l.fillRange(_startOffset(l, start), _endOffset(l, end), value);
diff --git a/modules/angular2/src/core/facade/collection.ts b/modules/angular2/src/core/facade/collection.ts
index 632612bfad..f26145c119 100644
--- a/modules/angular2/src/core/facade/collection.ts
+++ b/modules/angular2/src/core/facade/collection.ts
@@ -245,7 +245,6 @@ export class ListWrapper {
     return false;
   }
   static clear(list: any[]) { list.length = 0; }
-  static join(list: any[], s: string): string { return list.join(s); }
   static isEmpty(list: any[]): boolean { return list.length == 0; }
   static fill(list: any[], value: any, start: number = 0, end: number = null) {
     list.fill(value, start, end === null ? list.length : end);
diff --git a/modules/angular2/src/core/forms/directives/shared.ts b/modules/angular2/src/core/forms/directives/shared.ts
index 8c28c5a060..7d577e7bfe 100644
--- a/modules/angular2/src/core/forms/directives/shared.ts
+++ b/modules/angular2/src/core/forms/directives/shared.ts
@@ -42,7 +42,7 @@ export function setUpControl(control: Control, dir: NgControl): void {
 }
 
 function _throwError(dir: NgControl, message: string): void {
-  var path = ListWrapper.join(dir.path, " -> ");
+  var path = dir.path.join(" -> ");
   throw new BaseException(`${message} '${path}'`);
 }
 
diff --git a/modules/angular2/src/http/url_search_params.ts b/modules/angular2/src/http/url_search_params.ts
index 1a998c2e9b..e020fb8bc2 100644
--- a/modules/angular2/src/http/url_search_params.ts
+++ b/modules/angular2/src/http/url_search_params.ts
@@ -130,7 +130,7 @@ export class URLSearchParams {
     MapWrapper.forEach(this.paramsMap, (values, k) => {
       ListWrapper.forEach(values, v => { paramsList.push(k + '=' + v); });
     });
-    return ListWrapper.join(paramsList, '&');
+    return paramsList.join('&');
   }
 
   delete (param: string): void { MapWrapper.delete(this.paramsMap, param); }
diff --git a/modules/angular2/src/test_lib/utils.ts b/modules/angular2/src/test_lib/utils.ts
index 90085ad8d9..78907b5537 100644
--- a/modules/angular2/src/test_lib/utils.ts
+++ b/modules/angular2/src/test_lib/utils.ts
@@ -21,7 +21,7 @@ export class Log {
 
   clear(): void { this._result = []; }
 
-  result(): string { return ListWrapper.join(this._result, "; "); }
+  result(): string { return this._result.join("; "); }
 }