Thirty nonalcoholic young (18 to 30 years) males with extensive multigenerational family histories of male alcoholism and 29 age-matched, family history-negative controls completed a variety of trait personality questionnaires, participated in a competitive stress task (while sober and alcohol-intoxicated), and were assessed for self-report and laboratory drinking behavior. Low academic achievement, disinhibited personality (as measured by the P Scale of the Eysenck Personality Questionnaire), and sensitivity to alcohol reinforcement were significant and powerful independent predictors of self-report (approximate R2 = 0.40, p < 0.0001) and laboratory (approximate R2 = 0.20, p < 0.0001) drinking behavior. There seemed to be some specificity with respect to the facets of drinking behavior accounted for by each independent variable: low academic achievement and sensitivity to alcohol reinforcement were more related to quantity of alcohol consumption and frequency of excessive consumption, whereas psychoticism was more related to self-reported negative consequences with alcohol. A cluster analysis on three identified correlates of drinking behavior indicated that the two experimental groups could be more accurately subdivided into three homogeneous types. Multigenerational family history males were disproportionately represented in two of these groups: one characterized by enhanced sensitivity to alcohol reinforcement and the other characterized by high psychoticism scores and alcohol-related problems.