AbstractPrevious research has cluster analyzed MMPI profiles of adult substance abusers, particularly alcoholics. This is the first study to cluster analyze MMPI profiles of adolescent substance abusers (n = 250). Three clusters were found which were characterized by: (1) an apparently high level of psychopathology; (2) an impulsive, acting‐out style; and (3) a lack of marked psychopathology (no clinically significant elevations). The three clusters were validated by differences between the subjects on seven variables. These results are discussed in relation to previous cluster analyses of MMPI profiles of adult substance abusers, primarily alcoholics. Etiology of psychopathology in adolescent substance abusers and treatment recommendations are made based on the observed clusters.