The relationships between muscle-tension level, motoric-activity level, and academic performance in the laboratory setting are investigated. Three participants were reinforced for reducing and increasing their tension levels, alternately, while engaged in a simulated academic task, and the effects of each on the rate of activity and academic performance were measured. Measures were also obtained on the rate of activity and occurrence of problem behavior in the subject's homes. Significant treatment differences were found which support a direct relationship between tension and activity level so that a decrease in EMG level was associated with a decrease in motoric activity, and an increase in EMG level was associated with an increase in motoric activity. The efficacy of using EMG biofeedback to train relaxation in children with activity-level problems to control their symptoms is supported, especially where such a technique can be used in a specific task-oriented situation.