The purpose of the current study was to examine the mediating role of anger proneness in explaining the relationship between masculine gender role stress (MGRS) and aggression. Additionally, the moderating effect of anger proneness was also examined. Both physical and verbal forms of aggression were examined in the current model. Participants were 163 male undergraduate students. The criteria proposed by Baron and Kenny (1986) and Holmbeck (1997, 2002) were followed to test for mediational and moderational effects. Hierarchical regression analyses were conducted. Results indicate that anger proneness does mediate the relationship between MGRS and aggression, particularly physical aggression. Tests for moderated effects were not supported. The clinical and theoretical implications of these findings are discussed.