This paper describes a study which evaluates two classroom innovations directed at the problems of student motivation, academic performance, and social perceptions. These innovations, "Student Learning Teams" and "Academic Divisions," are evaluated in a two by two factorial field experiment in eight seventh grade English classes (the teams and divisions versus no teams, no divisions comparison was replicated in two additional schools.) The treatments were as follows: Control students worked individually. Cooperative work was allowed, but not encouraged. Students received scores on their quizzes. No Teams, Achievement Divisions: Same as control, except that students were assigned to homogeneous achievement divisions based on past grades in English. At the end of each week, each student's score on the sum of two quizzes was compared to that received by the others in his or her division. Students' individual divisional points were reported in a weekly class newsletter. Teams, No Achievement Divisions: Same as control, except that students were assigned to teams. Each team was made up of a high achiever, a low achiever, and average achievers. Students tutored each other. At the end of the week, a newsletter announced the teams with the highest point averages. Teams and Achievement Divisions: This treatment incorporated both the team and division components. In summary, the results are favorable toward the Student Teams- Achievement Divisions (STAD) combination. STAD is more effective than the control in increasing academic achievement, peer support for academic performance, liking of others, and number of students cited as friends. (Author/JM)