This volume explores the value of teacher collaboration in meeting the needs of diverse English language learners (ELLs). A range of research-based chapters demonstrate examples of effective collaboration between English language specialists and content area teachers and offer recommendations for collaborative practice. Foregrounding the ways in which teacher collaboration can better support the needs of ELLs in elementary, middle, and high school classrooms, this volume provides evidence-based insights and suggestions to underpin effective teacher collaboration across the curriculum. Through case study examples, readers can understand common challenges and pitfalls, as well as best practices and how to apply teacher collaboration in real classroom settings. Research studies in subject areas including mathematics, science, and English language arts provide a basis for practical, evidence-based recommendations to engender mutual trust, teacher agency, and the development of shared goals to enhance instruction for ELLs' achievement. This book provides educators with new insights from empirical studies, and is vital reading for researchers, scholars, teachers, and teacher educators who are aware of the importance of collaboration for student success. Those involved in ESL, bilingual, and dual language programs may be particularly interested in this volume.