A complete clinical evaluation is the critical first step in understanding the underlying dynamics, motivation, and etiology of adolescent homicide. This involves obtaining information on the alleged homicide, a history of the current illness, past history, ancillary history, clinical interviews with the juvenile, parent interviews, other interviews, psychological testing, and the physical examination. Treatment planning for mentally ill juveniles should focus on residential treatment, neuroleptic medication, supportive psychotherapy, and long-term aftercare planning. Return to the community, even with adequate preparation for outpatient care, should be carefully deliberated. Treatment for youth who commit homicide in the context of family or peer conflict must focus on interpretive psychotherapy, residential treatment, and careful discharge planning and family therapy. Treatment of juveniles who commit homicide during another crime should facilitate passage through the juvenile justice or adult court system; supportive psychotherapy and brief treatment with antianxiety agents are appropriate. 41 references.