The lack of social support has consistently been identified as a relevant factor in the development, maintenance, and treatment of posttraumatic stress disorder (PTSD). Prospective studies with combat veterans have supported the erosion model of social support in the development of PTSD. This model posits that increased PTSD symptoms lead to diminished social support over time. Additional epidemiological work that has investigated mental health and functional impairment in recently returning Operation Iraqi Freedom and Operation Enduring Freedom (OIF/OEF) veterans has suggested that interpersonal problems coincide with the onset of PTSD. Despite research that suggests OIF/OEF veterans experience high rates of PTSD and associated interpersonal problems, no studies have examined social support in relation to treatment response in this group. The current study examined the role of four theorized functional aspects of social support— emotional/informational support, positive social interactions, affectionate support, and tangible support— on pretreatment PTSD symptom severity and treatment response in a sample of OIF/OEF veterans receiving exposure-based psychotherapy. Findings showed that positive social interactions were negatively correlated with pretreatment symptom severity, and emotional/informational support was positively related to increased treatment response. Together, these findings suggest that specific types of social support may have an important influence on the course of exposure treatment.