This volume explores the defining element in the work of language teacher educators: language itself. The book is in two parts. The first part holds up to scrutiny concepts of language that underlie much practice in language teacher education yet too frequently remain under-examined. These include language as social institution, language as verbal practice, language as reflexive practice, language as school subject and language as medium of language learning.The chapters in the second part are written by language teacher educators working in a range of institutional contexts and on a variety of types of program including both long and short courses, both pre-service and in-service courses, and teacher education practice focusing variously on metalinguistic awareness for teachers, language improvement, and classroom communication. The unifying factor is that collectively they illuminate how language teacher educators research their practice and reflect on underlying principles.