This study represents a collaborative school university partnership. Using a mixed-method approach, the authors report on the motivational and psychological consequences of students choosing their groupmates in cooperative learning triads. 139 students in five science classes participated in this study. Classes were randomly assigned to condition: Teacher-selected or student-selected. In teacher-selected classes, the teacher chose the members of each group; in student-selected classes, the students chose their groupmates. Results revealed a decrease in willingness to choose one's groupmates. Focus group data indicated that students felt obligated to choose friends as groupmates, and low-achieving students questioned the value of working with similar others. Teachers should be aware that when permitting students to choose their groupmates that friendships and status hierarchies exert strong influences on choice of partner. (Contains 3 tables and 1 figure.)