This book reviews classroom-based research and attempts to provide confirming or disconfirming evidence for claims about the influence of language instruction and classroom interaction on language learning. This is achieved by comparing studies that describe teachers? and learners? behaviors in classrooms and synthesizing them into generalizations about the processes that take place in second language classrooms. Studies that point to relationships between these behaviors and second language development are also summarized. Classroom teachers, school administrators, teacher trainers, and second language researchers should all find in the review of these relationships useful implications for language teaching, language curriculum development, and further research goals. Theories and claims about language teaching methods, effective curriculum, or the importance of learner characteristics have rarely been based on actual research in language classrooms, despite the integral role that classroom teaching and learning plays in theoretical and practical proposals.