How can one measure the effects of a drug that acts upon the mind and the emotions of a child? Unlike adult patients, children rarely ask for symptomatic relief; they are given psychoactive drugs because others complain about their behavior. The drugs are given to alter behavior rather than subjective feelings. The evaluation of drug effect, then, depends upon observed changes in behavior. In a residential treatment setting, members of the staff can observe the child's behavior; with outpatients the physician must rely on his own observations and information from parents and school personnel. This two-year study examines home, school, and clinic perspectives of children receiving psychoactive drugs. Because they influenced the design of our drug-evaluation program, we shall first call attention to some problems encountered in previous psychopharmacological clinical research with children (Fisher, lQ59; Forster, 1961; Freed, 1962). Many workers stress the importance of defining specific, observable symptoms, like hyperactivity, as the target of the drug rather than more abstract syndromes, such as anxiety. The rating method should be validated by using more than one observer in order to minimize the bias inherent in the viewpoint of one