Student Team Learning instructional techniques (Teams-Games-Tournament, Student Teams-Achievement Divisions, and Jigsaw II) have been extensively researched in six-to-twelve-week classroom experiments and found to have many positive effects. This study examines the effects of the techniques when they are used as the primary instructional method for a full semester in language arts, math, and social studies. The subjects were 388 fourth- and fifth-grade students in five elementary schools, two of which served as experimental schools and three as controls. The experimental groups scored significantly higher on four of seven Comprehensive Test of Basic Skills (CTBS) subscales than did the control groups. No significant differences were found for affective variables measured, except that the experimental groups named significantly more "friends in school." (Author/MP)