Two basic approaches characterize classroom research on second language learning: interaction analysis and anthropological observation. Within each approach several methods are available for data collection and analysis. Procedures described are the use of behavioral observation systems, discourse analysis, ethnography, constitutive ethnography, and diary studies. Strengths and limitations of these methods and of both basic approaches are considered, and suggestions are made for the design of future research. This work needs to include a classroom observational component in which language acquisition as well as classroom process variables are treated. In this way it will be possible to test a theory of second language acquisition with the aid of formal instruction.