While Veterans in general are no more dangerous than the civilian population, Veterans with posttraumatic stress disorder (PTSD) have stronger associations with anger and hostility and certain forms of aggression, such as intimate partner violence, than civilians with PTSD. This is alarming because up to 21% of Veterans seeking Veterans Affairs (VA) health care are diagnosed with PTSD. Emotion regulation difficulties (emotion dysregulation) are also related to increased PTSD symptom severity and may play a role in aggressive behavior. Because the predominant form of aggression in PTSD appears to be the impulsive subtype, the authors sought to clarify the relationship between PTSD, emotion dysregulation, and impulsive aggression. We examined how emotion dysregulation influenced impulsive aggression in a Veteran sample (N = 479) seeking treatment for trauma sequelae. All Veterans completed measures that assessed demographic information, emotion dysregulation, aggression frequency and subtype, and PTSD symptoms. Men generally reported more aggression than women. The emotion dysregulation, aggression, and PTSD measures were significantly correlated. Two cross-sectional mediation models showed emotion dysregulation fully accounted for the relationship between PTSD and impulsive aggression (indirect path for men: b = .07, SE = .026, bias-correct and accelerated confidence interval [BCa CI] = [0.02, 0.13]; indirect path for women: b = .08, SE = .022, BCa CI = [0.05, 0.13]). PTSD can increase negative emotions yet does not always lead to aggressive behaviors. The ability to regulate emotions may be pivotal to inhibiting aggression in those with PTSD. PTSD interventions may benefit from augmentation with emotion regulation skills training.