The purpose of this investigation was to examine the moderating role of family history (FH) of alcohol use disorders on the association between positive alcohol expectancies and drinking behavior (quantity/frequency of drinking and alcohol-related problems). Lifetime DSM-III-R diagnoses of alcohol abuse/dependence in probands from the Yale Family Study were used to classify FH status of adult relatives, yielding 149 relatives of probands with alcohol abuse/dependence and 110 relatives of controls. Significant main effects were found for FH of alcoholism on problem drinking symptoms and for alcohol expectancies concerning both problem drinking symptoms and quantity/frequency of alcohol use. Regarding moderating effects, there was a significant interaction between alcohol expectancies and FH only for problem drinking symptoms. When familial density of alcoholism was examined as a moderator, significant effects were found for all drinking variables, thus demonstrating that the degree to which alcohol expectancies was associated with the drinking outcomes varied by the extent to which alcohol use disorders clustered in families. The findings are discussed in terms of the interaction of alcohol-related risk factors and the importance of using multiple indicators of familial vulnerability.