This study investigated the social behavior patterns of children who worked on a cooperative task. Several ways of increasing interdependence were explored, and the effects of such methods on task performance were determined. Seventy six same-sex triads of fourth and fifth graders were asked to cooperate in making a block-picture on a round board. All conditions included goal-interdependence; they differed systematically in presence of task requirements, task roles, and group roles. Behavior was precoded in various group-oriented and individual-oriented categories. A Productivity Index was constructed. As hypothesized, goal-interdependence alone did not maximize occurrence of cooperative behavior. Performance was poorest when task requirements and role assignments were absent. Pro-social behavior and performance was significantly greater where task requirements, task roles, and group roles were present together. A strong consistent pattern of sex differences was found, with boys showing greater independence from experimental role-inductions. (Author/DP)