Rich and diverse, the research draws on more than 100 case studies of action learning by teams of teachers in schools. The authors: Addressing the highs and lows, the successes and failures, and their underlying causes, provides insights into theories of cooperation, innovation, leadership and community formation to inform individual projects and large-scale school improvement initiatives. It will be of interest to teacher educators, pre-service and experienced teachers alike, as well as school and education system managers and policymakers keen to enhance teacher professional learning and educational outcomes for students.