This study examined social skills deficits as a mediator of the relationship between posttraumatic stress disorder (PTSD) symptoms and use of intimate partner aggression (IPA) among returning veterans. Prior research with veterans has focused on PTSD-related deficits at the decoding stage of McFall’s (1982) social information processing model, and the current study adds to this literature by examining social skills deficits at the decision stage. Participants were 92 male veterans recruited from the greater Boston area. PTSD symptoms were assessed through clinician interview, IPA use was assessed through self- and partner report, and social skills deficits were assessed in a laboratory task in which veterans listened to a series of problematic marital situations and responded with what they would say or do in the situation. Responses were coded for social competency. Bivariate correlations revealed several significant associations among PTSD symptoms, social skills deficits, and use of IPA. When all PTSD symptom clusters were entered into a regression predicting social skills deficits, only emotional numbing emerged as a unique predictor. Finally, social skills deficits significantly mediated the relationship between veterans’ PTSD symptoms and use of psychological (but not physical) IPA. Findings extend prior research on McFall’s (1982) social information processing model as it relates to veterans’ PTSD symptoms and use of IPA. More research is needed to understand the associations between PTSD symptoms and deficits at each individual step of this model.