This book represents the first collection of studies on Content and Language Integrated Learning (CLIL) which brings together a range of perspectives through which CLIL has been investigated within Applied Linguistics. The book aims to show how the four perspectives of Second Language Acquisition (SLA), Systemic Functional Linguistics (SFL), Discourse Analysis, and Sociolinguistics highlight different important aspects of CLIL as a context for second language development. Each of the four sections in the book opens with an overview of one of the perspectives written by a leading scholar in the field, and is then followed by three empirical studies which focus on specific aspects of CLIL seen from this perspective. Topics covered include motivation, the use of tasks, pragmatic development, speech functions in spoken interaction, the use of evaluative language in expressing content knowledge in writing, multimodal interaction, assessment for learning, L1 use in the classroom, English-medium instruction in universities, and CLIL teachers' professional identities.