Cooperative learning has broad support as an instructional strategy to improve achievement. If the social behavior of students at risk for ADHD could be documented, cooperative groups could also provide a context for intervention. To this purpose, we observed 22 same-gender triads, with or without a member at risk for ADHD during problem-solving performance. Findings were that at-risk students exhibited more negative verbal, off-task, and less cooperative behavior. Unexpected findings were that their groups were also more successful. Educational implications when planning group experiences were described in terms of (a) the identification of behavior to anticipate from students at risk, (b) how students' behavior can alter the behavior of their general education peers, and (c) the importance of interventions for all group members, especially boys. (Contains 6 notes, 4 tables, and 2 figures.)