Ways in which classroom learning environments contribute to the failure of modern school systems to serve ethnic and minority groups in large urban centers are analyzed in this ethnographic study. The study, which took place in the elementary schools of the Berkeley Unified School District, consisted of collecting ethnographic information on the school setting, classroom interaction, student family and cultural background, and peer networks; selection of key episodes; conversational-linguistic analysis of episodes; and search for comparative ethnographic data and conversational data to test the assumptions of the research. Thus, the research consisted of a comparative study within classrooms with a focus on children in high and low reading groups and between home and school. Results of this and other studies are summarized within six categories: learning and teaching as an interactive process, differential access to learning opportunities, oral and written schemata, social network influences on school children, informal learning in home and school, and methodological observations on ethnography and natural experiments. Appendices, which form the major portion of the document, include additional notes on the collection of data, several transcripts of conversations, outlines of typical days in various grades, and several research papers related to the topic of this study. (KC)