Because of the availability of new technology for measuring 24-hour motor activity, the NIH actometer, a study has been conducted to examine activity levels of hyperactive children and matched controls during a baseline week. Following this, motor activity of the hyperactive group was compared during amphetamine and placebo treatment periods. This is the first study to examine drug effects on motor activity outside of a laboratory setting. Drug effects were examined in relation to measures of structure of classroom and home environment. Actometer data was compared with traditional clinical measures for hyperactive children.