The 40 male and 31 female subjects were all housed in the training school system in Michigan. The subjects all met two or more of four criteria: (1) commission of violent felonies, (2) commission of multiple nonviolent felonies, (3) multiple placements in the training school system, and (4) assaultive in-program behavior requiring medical attention for the victim. Subjects all completed a 51-item delinquency checklist, a semistructured interview, and the Schedule for Affective Disorders and Schizophrenia (SADS), after which two evaluators agreed on RDC and DSM-111 diagnoses. Subjects and evaluators also completed rating scales for depression. A wide range of psychopathology was identified, with all subjects receiving multiple psychiatric diagnoses. Substance abuse or alcoholism, borderline personality disorder, and major or minor affective disorders were the most common diagnoses. Measures associated with the severity of delinquency and adult antisocial outcome were most clearly associated with borderline personality disorder and substance abuse. Research recommendations, treatment implications, tables, and 72 references.