CLIL (Content and Language Integrated Learning) has been a major trend in education since the turn of the millennium. Written by Do Coyle, Philip Hood, and David Marsh, and based on their experiences with CLIL in secondary schools, primary schools, and English language schools across Europe, this book offers a comprehensive overview of CLIL. It summarizes the theory underlying the teaching of subject matter through another language and discusses its practical application. It also outlines key directions for the development of research and practice. While acknowledging the uncertainty many teachers feel about CLIL due to its demands on both language and subject matter knowledge, this book offers theoretical and practical pathways to successful applications for all.