The purpose of this study was to investigate the influence of irritability on alcohol-related aggression in men and women. Subjects were 204 (111 men and 93 women) healthy social drinkers between 21 and 35 years of age. Irritability was measured using the Caprara Irritability Scale. Following the consumption of either an alcohol or a placebo beverage, subjects were tested on a modified version of the Taylor Aggression Paradigm in which mild electric shocks were received from, and administered to, a fictitious opponent during a competitive task. Aggressive behavior was operationalized as the shock intensities administered to the fictitious opponent under conditions of low and high provocation. Of all the variables, provocation was the strongest elicitor of aggression. Overall, irritability was positively related to aggression for all subjects. The finding of greatest importance was that alcohol increased aggression for persons with higher, as opposed to lower, levels of irritability. However, this pattern of results was only evident for men. The results highlight the fact that alcohol consumption does not increase aggression in all persons and in all situations. An important goal for future research is to identify which individual differences and which contextual factors are most important in determining who will, and who will not, behave in an aggressive manner when intoxicated.