Preadolescents are faced with a variety of pressures, but usually receive little help in stress management from the school. To examine the effects of relaxation training on rural middle school students (N = 532), researchers implemented a daily 15-minute program of relaxation training exercises on aduio tapes in the regular classroom setting. The students recorded their wrist temperatures before and after each exercise as a measure of the relaxation state. Researchers examined five dependent variables and compared the performance of students in the experimental group with a randomized control group. Absenteeism and tardiness showed no significant differences between experimental and control groups. The experimental students, however, had significantly fewer discipline problems than the control group, indicating that relaxation training has a positive effect on problem behavior. Also, while no overall experimental/control difference was found on a measure of self-concept, females in the experimental group did appear to have higher self-concept scores than females in the control group. Finally, while there was no overall difference between the experimental and control groups in achievement, the experimental groups which excelled at relaxing, as measured by wrist temperatures, scored significantly higher than their paired control groups. Experimental groups with poor relaxation skills scored equal to or lower than their control groups. This finding suggests the existence of a threshold of relaxation, a level necessary for cognitive gains. (Author/JAC)