A 14-year-old male adolescent who evidenced both inconsistent diabetic self-care and antisocial behavior was treated using behavioral family therapy. An extended baseline assessment of self-care, antisocial behavior and mother-child conflict indicated a cyclic coercion-countercoercion process in which the mother's attempts to discipline the son's antisocial behavior resulted in the son's deliberate poor self-care until a diabetic episode occurred, terminating his mother's disciplinary actions. Treatment sequentially focused on self-care, antisocial behavior, mother-child conflict, and school attendance and behavior. Self-monitoring and a reinforcement salary were insufficient to alter self-care; the addition of a potent punishment for poor self-care led to improved self-care and less frequent diabetic crises but increased antisocial behavior. Maternal monitoring of the son's activities and peer associates, a behavioral contract, and communication/problem-solving training resulted in a reduction in antisocial behavior and conflict, and in increased school attendance. Treatment gains were maintained at a two-month follow-up.