Never before has there been such widespread agreement among researchers and practitioners regarding the most promising approach to significantly improve schools. Researchers, writers, and educational organizations have all endorsed the concept of schools functioning as professional learning communities. At the same time, the concept will have little impact on schools unless professional learning community practices become embedded into day-to-day school culture. If professional learning communities offer the best hope for school improvement, a critical question facing educators is this: How can we develop school cultures that reflect the ideals and practices of professional learning communities? The authors have found that collaboratively developed shared values and commitments can be a powerful tool for shaping school culture. In this article, the authors discuss the significance of establishing explicit shared commitments as one of the most effective tools to those seeking to implement professional learning communities in their schools and districts.