Content and language integrated learning (CLIL) is an increasingly popular educational approach given its dual focus on enabling learners to acquire subject-matter through an additional language, while learning this second language in tandem with content. This handbook provides a comprehensive overview of recent CLIL developments, illustrating how CLIL has been uniquely conceptualized and practiced across educational and geographical contexts. Divided into six sections, covering language and language teaching, core themes and issues, contexts and learners, CLIL in practice, CLIL around the world and a final section looking forward to future research directions, every chapter provides a balanced discussion of the benefits, challenges and implications of this approach. Representing the same diversity and intercultural understanding that CLIL features, the chapters are authored by established as well as early-career academics based around the world. The Routledge Handbook of Content and Language Integrated Learning is the essential guide to CLIL for advanced students and researchers of applied linguistics, education and TESOL.