This book focuses on sustaining communities of practice in primary and secondary schools in Australia and internationally for the professional learning of all teachers, and particularly, early career teachers. Informed by the communities of practice research of Wenger-Trayner, it shows what factors are conductive to the sustainability of communities of practice, drawing particularly on a case study of an Australian regional secondary school, and explores how it has sustained support particularly for early career teachers over a three-year period. The first chapters of the book provide longitudinal perspectives using qualitative data and include perspectives from a variety of stakeholders, including the principal, the professional learning coordinator and the early career teachers who have experienced the school’s Communities of practice over three or more years. It offers practical suggestions on how to implement and improve communities of practice in schools and highlights the increasing importance of online communities to support early career teachers. Policy-makers, school principals, teacher educators and teaching practitioners find the book useful for implementing and sustaining communities of practice in schools. Subsequent chapters explore the value of online communities, such as Twitter communities; the role of collegial support networks in supporting early career teachers in Flemish primary education; and professional learning in Northern Ireland pre- and in-service teacher networked communities.