Based on research and many years of lived experience in schools, the authors have become convinced that teachers learn best within their own work communities. In this volume, they explore what research and practice have to tell us about how such communities grow and develop, and how to negotiate the inherent tension between improving competence and building community. Using five themes that emerged from their studies of practice (context, capacity, content, commitment, and challenge), the authors examine selected research studies, personal reflections, and five cases that were especially commissioned for this volume in order to uncover new insights and understandings.