This study is the final report of an investigation into the effectiveness of Student Teams Achievement Divisions (STAD), a system of cooperative learning at the postsecondary level. The study specifically examined the relationships between a student's evaluation of his/her own effectiveness as a STAD team member, and other variables in a collaborative educational psychology course. Students (n=154) were assigned to eight heterogeneous teams which met together weekly to work on projects. At the end of the semester students rated both the course and themselves and their team members. The study found: (1) a substantial positive correlation between the student's self-rating and the rating given him/her by other team members; (2) a substantial positive correlation between the student's self-rating and the mean rating given to other team members; (3) a modest, positive correlation between the student's self-rating and the student's evaluation of the course; (4) a modest positive correlation between the student's self-rating and the student's evaluation of the teacher's motivational decisions; and (5) positive correlations between the student's self-rating and most of the student's formal grades. Appended are data tables, course rating scales, and team member performance appraisal forms. (Contains 18 references.) (DB)