Two experiments examined the behavioral effect of alcohol on male social drinkers aged 19-25, who differed in their family histories of problem drinking--21 reported a problem drinker in their immediate family (FH+) and 22 had no such family history (FH-). These groups did not differ in age, weight or absolute alcohol per kg of body weight typically consumed on social occasions. After drinking absolute alcohol (0.83 ml/kg), subjects performed bead stringing and hand steadiness tasks when their blood alcohol levels (BALs) averaged 63 mg/dl on the rising and the declining limb of the BAL curve. The experiments consistently demonstrated that FH+ individuals displayed a greater degree of impairment on the tasks. One of the experiments also explored subjective ratings of the effects of alcohol at matching BALs and found no significant group differences. The greater behavioral sensitivity to alcohol of FH+ subjects and their apparent absence of a concomitant enhanced perception of its effects were discussed as a potential component of their higher risk of developing problem drinking.