The experiences in the school districts highlighted in this article clarify a set of broad goals that all professional learning communities can use to assess their effectiveness: (1) Culture; (2) Knowledge; (3) Practice; and (4) Achievement. These schools and districts have an ongoing commitment to all four goals. All of them have instituted learning clubs, established a common language, examined and refined instructional practices, and paid close attention to the impact this work has had on student achievement. Using these goals, the schools and districts provide the resources and support teachers need to become more effective educators. The professional learning community movement has taught educators that "a collection of superstar teachers working in isolation cannot produce the same results as interdependent colleagues who share and develop professional practices together." This means that professional learning communities are key to the development, nourishment, and continued success of effective educators, an idea widely supported by research, including an extensive study conducted by the National Commission on Teaching and America's Future (2010).