The present investigation tested the hypothesis that executive functioning (EF) would mediate the relation between difficult temperament (DT) and aggressive behavior. This model was tested in 310 adult men and women. DT was measured using the Dimensions of Temperament Scale—Revised, EF was measured using 7 well-established neuropsychological tests, and aggression was assessed using the Buss–Perry Aggression Questionnaire. EF successfully mediated the DT–aggression relation for men, however, the model did not hold for women. Results are discussed with regard to how they influence current models of aggressive behavior as well as their implications for future violence prevention efforts.