The current study tests a theoretical model illustrating a potential pathway to reactive aggression through exposure to a traumatic event (Hurricane Katrina) in 166 adolescents (61% female, 63% Caucasian) recruited from high schools on the Gulf Coast of Mississippi. Results support an association between exposure to Hurricane Katrina and reactive aggression via posttraumatic stress disorder (PTSD) symptoms and poorly regulated emotion. The proposed model fits well for both boys and girls; however, results suggest that minority youth in this sample were more likely to experience emotional dysregulation in relation to posttraumatic stress than Caucasian youth. Further, results indicate that hurricane exposure, PTSD symptoms, and poorly regulated emotion are associated with reactive aggression even after controlling for proactive aggression. These findings have implications for postdisaster mental health services. Researchers examining mental health problems in youth after a significant disaster have traditionally focused on the presence of internalizing problems such as anxiety, depression, and posttraumatic stress disorder (PTSD) symptoms, with very little empirical attention paid to the incidence of post-disaster externalizing problems such as aggression. Specific types of aggressive responses, particularly those that involve poorly regulated emotion (i.e., reactive aggression), have been shown to be associated with a history of trauma and thus may be especially common following a traumatic event such as a hurricane. (Contains 1 figure and 2 tables.)