This book explores the topic of teacher cognition, making use of sociocultural theory as a framework to understand what teachers know, think, believe and do in their professional contexts through 'applied' conversation analysis. The author examines what teaching and learning mean to teachers by analyzing the interactional work they do with their students, considering when and why teachers make interactive decisions as well as how they utilize new technological tools to address their pedagogical objectives. After discussing how teachers construct identities and display emotions in the classroom, she presents suggestions for language teacher education and development, pedagogy improvement and teacher knowledge. This book will be of interest to language teachers and teacher trainers, as well as students and scholars of applied linguistics and sociocultural theory.