Abstract
Analyses of the MAC Scale scores of male substance abusers evidence the presence ot two fundamentally different, age-independent characterological types within unselected runs of male alcohol and drug abusers. Examination of those items which best accomplish this discrimination indicates that the members of the majority type (approximately 85%, on average, over several studies) have disorders of character, while the members of the minority type (approximately 15%, on average, over several studies), are introverted neurotics. Since both types are also present, but in roughly opposite proportions, in the self-depictions of the members of unselected runs of nonsubstance-abusing male psychiatric outpatients, it is evident that neither type is comprised only of substance abusers.