Do teacher leaders in your school mainly fill the traditional roles of department chair or grade-level representative? Or do they lead their peers in collaborative teams whose primary focus is improving student learning? Terry Wilhelm, director of the School Leadership Center for Riverside County Office of Education in California, says that today's high accountability demands require teachers to assume the latter role. In a shared leadership school-often called a professional learning community-teacher leaders guide and manage the work of teams consisting of course-alike or grade-level peers who work directly in the areas of curriculum, instruction, and assessment. In a shared leadership school, the role of the principal also changes. Principals must strike a delicate balance, providing needed direction while supporting teacher teams' creativity and initiative. In this article, Wilhelm gives examples both of common mistakes principals make in implementing shared leadership, and of principals who have succeeded in striking this balance. She also describes how a school or districts might construct a process for providing essential training to help teacher leaders assume their new shared leadership role.