States that the combination of group rewards (based on group members' individual learning) and peer interaction on learning tasks is necessary to produce learning gains characteristic of effective cooperative learning methods. Discusses research on group contingencies and cooperative learning in the elementary school classroom.(NH)

Reports several field experimental research studies which tested the effects of group and individual incentive structures and tasks on individual academic achievement. The positive effects of cooperative learning methods result from the use of cooperative incentives, not cooperative tasks, apparently due to change in peer norms. (CB)