The motor activity of hyperactive and normal boys was studied in 12 age- and classroom-matched pairs. Activity was measured continuously for a one-week period with a portable solid-state monitor. Hyperactives exhibited generally higher levels of motor activity than normal controls regardless of the time of day, including during sleep and on weekends. In a situation-by-situation analysis, hyperactives were most consistently and significantly more active than the controls during structured school activities. Little evidence was found, however, to support the hypothesis that hyperactivity is simply an artifact of the structure and attentional demands of a given setting. Pervasive increases in simple motor behavior are a clear attribute of hyperactive behavior and distinguished hyperactives from controls as well as did a standardized measure of attention.