Hyperactivity in children is explained in relation to behavioral characteristics, precipitating factors, and stimulant medication therapy. The basic mechanism of hyperactivity is seen to be impulsive style in motility, attention, and socialization. Problems caused by impulsivity are noted to include feeding problems, school difficulties, and peer alienation. Two factors are reported to precipitate hyperactivity which are emotional (stress) and chemical (food additives). The use of stimulant medication therapy is discussed in terms of goals; type and advantages of drug chosen; dosage; when to stop medication; and effects on growth, appetite, and sleep. (SB)