In cooperative learning environments, small groups of students work together to accomplish specific pedagogical tasks, and teachers act as facilitators. One highly significant characteristic of cooperative learning that has received little consideration so far is the shift in the participation frame that takes place when students are left alone to work on classroom tasks rather than having the teacher direct the learning process. Students are free to take their own time to work out their learning strategies, and they rely on peer group processes both to establish collaboration and guide their own learning. It is in such exchanges that learning processes can be made into observable activities. Central to the case studies described in this report is the fact that everyday informal conversational exchanges play an essential role in group processes, where one speaker is given primary rights of speaking, but where participants must compete for the floor and cooperate in achieving shared communicative tasks. The cases presented here are drawn from the Cooperative Integrated Reading and Composition (CIRC) database, which includes approximately 200 hours of 90-minute video recordings collected through ethnographic field work in third and fourth grade bilingual classrooms over a period of 3 years. The focus is on in-depth conversational and interactional sociolinguistic analysis of selected excerpts that illustrate key learning and teaching issues that arise in cooperative learning situations in monolingual and bilingual classrooms. (Contains 27 references.) (Author/KFT)