This paper reports on a pilot investigation designed to test the effectiveness of perphenazine and placebo in producing changes in the behavior of a group of institutionalized Negro delinquent boys. Review of Literature In a study of 777 delinquents evaluated at the Judge Baker Foundation Clinic, the Gluecks classified 13% as showing "mental disease or distortion" and an additional 41% as exhibiting "marked personal liabilities or adolescent instability."1There is evidence to suggest that such a population breeds criminality2and mental illness.3,4The psychopathology reported in delinquent children usually includes aggressivity, impulsiveness, overactivity, and neurotic symptomatology, all of which have been listed as indications for ataractic drugs. Psychiatrists are being asked with increasing frequency to provide guidance for the management of emotionally disturbed children in the training school. Yet, the literature reflects a paucity of adequately controlled studies with delinquents, and we