The contributions of specific scales of the Minnesota Multiphasic Personality Inventory-Adolescent (MMPI-A) to the classification of 180 adolescent substance abusers into groups characterized by behavioral undercontrol (primary), an absence of behavioral undercontrol (secondary), and behavioral undercontrol and overcontrol (combined) were evaluated. Discriminant function analyses demonstrated that the MacAndrew Alcoholism-Revised (MAC-/?), 2 (Depression, or D), 4 (Psychopathic Deviant, or Pd), 9 (Mania, or Ma), 3 (Hysteria, or Hy), Alcohol/Drug Problem Proneness (PRO), and Alcohol/Drug Problem Acknowledgment (ACK) scales made significant contributions to the classification of participants into the 3 groups, and that discriminant functions involving these predictor variables resulted in the correct classification of 79.4% of the cases.