Book excerpt: Writing is one of the most challenging skills for a language learner to acquire due its sheer complexity, and language teachers are faced with a demanding task in the teaching and testing of writing. This book presents relevant conceptual and theoretical frameworks of second language writing research and sheds light on the implications of the recent research findings in a clear and practice-oriented style. In this way, it is intended as a companion book for language teachers who include writing as a part of their courses, in particular, new teachers as they embark on their teaching careers.