This book presents exemplars of multilingualism in TESOL worldwide. It incorporates essential topics such as curriculum development, classroom instruction, materials creation, assessment, and teacher training where TESOL and multilingualism co-exist and co-develop. The wide-ranging and international collection of chapters is written by leading researchers in multilingualism and TESOL from around the world. This handbook provides unique insights into a range of practical approaches to promote local, indigenous and national languages in English language classrooms across a range of instructional programs in various geographical contexts. The book is divided into six sections. Part 1 presents curricular and principle-based approaches to multilingual TESOL in ESL/EFL classes. Part 2 includes chapters that showcase how diverse teachers bring multilingual TESOL to their classrooms. Part 3 discusses the challenges of teaching multilingual TESOL and how educators address them in their contexts. Part 4 provides activities and materials to support local languages in TESOL classrooms. Part 5 addresses assessment issues in multilingual TESOL. Part 6 includes initiatives and examples to prepare TESOL teachers to promote multilingualism in ESL/EFL classrooms.