A discussion of classroom research on language teaching looks at what researchers have learned so far from attempts to study what happens in the language classroom. The discussion is based on the idea that it is not the currency of instructional method used that matters most, but rather a fuller understanding of classroom interaction. The first part examines the evolution of and rationale behind classroom research in general. The second part explores some major methodological issues, beginning with determining the research approach to take and proceeding to data collection and analysis. Parts 3-5 review the findings of language classroom research since the late 1960s in three areas: errors in oral language use; the complexities of classroom interaction; and aspects of learner receptivity, including anxiety, competitiveness, motivation, and self-esteem, as they relate to language learning. Part 6 closes with ideas about exploratory teaching, in which the teacher both tries new approaches and attempts to learn from their use. A section following each chapter contains ideas for starting discussion among teachers, and suggestions for further reading. Appended materials include notes on several methods of interaction analysis, observation of communication settings, transcription conventions for classroom discourse, a substantial bibliography, and author and subject indexes. (MSE)