This thought-provoking book examines the nature of second language teacher development and how teachers’ practices are influenced by their beliefs and principles. The book seeks to move discussion of language teacher development beyond the level of training, which reflects a technical view of specific teaching practices. Instead, it takes a more holistic approach to teacher development built on the notion of the teacher as critical and reflective thinker. The argument pursued throughout the book is that teacher education needs to engage teachers not merely in the mastery of techniques, but in an exploration of the knowledge, beliefs, and attitudes that underly their teaching practices.