This book explores multilingualism as a resource and goal at school in contexts of student diversity and institutional monolingualism. Combining translanguaging theory and sociocultural theory, the author proposes a framework for the learning and use of both foreign and heritage languages across the curriculum in mainstream schools. By clearly linking language practices to teaching and learning objectives, the book aims to support school leaders and practitioners make informed decisions about how best to promote multilingualism in their school, as well as to enhance the learning outcomes of bi/multilinguals. In addition to school leaders and practitioners, it will be of interest to students and academics in the fields of bilingual education and TESOL, as well as applied linguistics and language teaching more broadly.