This book is an examination of how and what teachers think in their practice of language teaching. It looks at the planning practices of teachers, both in preparation for the classroom and during the moment-by-moment decision-making that occurs in the classroom. It also looks at teachers' interpretive processes, that is how they interpret and evaluate the events, activities and interactions that occur in the teaching process, and how these interpretations and evaluations feed back into subsequent planning. It examines the structure of teachers' beliefs, assumptions and background knowledge and elaborates the role that these play in the decision-making process. This is an important contribution to the developing perspective in education of teachers as being actively involved in constructing a personal and workable theory of teaching and the learning/teaching experience as an interactive, dynamic process.