This article introduces the special section in the Journal of Traumatic Stress focused on social relationships and their connection to treatment among individuals with posttraumatic stress disorder (PTSD). Interpersonal relationships have the potential to influence treatment-seeking, retention, and outcomes. For individuals with PTSD, social relationships have long been understood to be intimately and bidirectionally tied to symptom levels. In light of somewhat modest rates of treatment response to current first-line interventions for PTSD, there is growing interest in engaging these relationships, as well as relationship-relevant beliefs and behaviors, to enhance PTSD treatment. This introductory article frames the rationale for examining these social factors to better understand and improve treatments and provides an overview of the collection of articles contained herein.