To sustain meaningful conversations about language education with students, colleagues, and other stakeholders within the widely ranging contexts of TESOL and bilingual education, it is important that practitioners and experts are conversant with key terms and concepts. Terminology related to TESOL and bilingual education is dynamic, nuanced, and evolving. This is particularly the case as teaching and research in relation to multilingual learners continue to expand. It is essential for educators of all kinds to be equipped with the necessary terminology and background knowledge. The Language of TESOL and Bilingual Education: An Expanded Glossary of Key Terms and Concepts provides clear definitions and context for critical terms and concepts related to English language teaching and bilingual education while also highlighting their practical applications and implications for teacher education. These connections facilitate a transition from a mere recognition and use of terminology to a more profound critical reflection on how these terms relate to one’s own beliefs and instructional practices. This volume is the perfect companion for any educator, university student, or scholar wishing to exercise their fine-tuned understanding and expression of multilingual learner education using important terms and considerations for practice.