Cooperative learning, as it was constructed in three seventh-grade classrooms in a multi-ethnic middle school, was examined as part of a dissertation study that focused on cooperative learning as embedded in its sociocultural context. Data were gathered using ethnographic methods, including participant and nonparticipant observations, document analysis, interviews, and audio recordings. The data were then constructed into vignettes of life in each of the three classrooms. The results suggest that the subject matter and social participation structure of cooperative learning are inextricably linked. However, the necessity of formal cooperative learning structures and procedures is questioned. Cooperative learning approach, subject matter, academic tasks, students' behavior and interactions, teachers' management styles, and other factors interacted in the three classrooms to constitute the enacted curricula, each providing markedly different learning opportunities. Teachers need to give careful consideration to the kinds of academic tasks that students work on in small groups to provide motivating, meaningful content that supports thinking and sharing of ideas. Contains 42 references. (MDM)