Recent investigations of the effects on group output of competitive contingencies, reward deliveries to group members contingent upon achieving a higher or lower task rate than another group, have suggested that competitive contingencies are a positive function of group output. When rewards are contingent upon a higher comparison outcome, group task rates increase, and when rewards are contingent upon a lower comparison outcome, the rates decrease. The present investigations examine the effects on group output of reward magnitude during competitive contingencies. The studies, conducted in a special education classroom of a junior high school, demonstrated that the greater the competitive contingent reward, the more likely that group output will increase or decrease according to the competitive contingency in effect, a reward to group members for a higher or lower task output than another group. The procedure employed that was designed to promote organized participation on "teacher directed activities" was the presentation of a "button press" task. (Author/BW)