The Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; DSM-IV-TR; American Psychiatric Association [APA], 2000) emphasizes life threat as the defining feature of psychological trauma. Recent theoretical and empirical work, however, indicates the need to identify and evaluate other key aspects of trauma. Betrayal has been proposed as a pertinent, distinct, and complementary factor that can explain effects of trauma not accounted for by life threat alone. This study examined the relationship between injury, perceived life threat (PLT), and betrayal with posttraumatic stress disorder (PTSD) symptom severity. Trauma-exposed college students (N = 185) completed self-report measures of trauma exposure and PTSD, as well as items regarding life threat, betrayal, and level of medical care received. In hierarchical regressions incorporating injury, PLT, and betrayal, betrayal was associated with all PTSD symptom clusters and PTSD total severity (f2 = .08), whereas PLT was associated with hyperarousal (f2 = .05) and PTSD total (f2 = .03), and injury had no association with PTSD symptoms. In a revised model with trauma type as an additional variable, betrayal was associated with avoidance (f2 = .03), numbing (f2 = .04), and PTSD total (f2 = .03), whereas PLT was associated with reexperiencing (f2 = .04), hyperarousal (f2 = .04), and PTSD total (f2 = .03), and injury was associated with avoidance (f2 = .03). These findings support the idea that betrayal is a core dimension of psychological trauma that may play an important role in the etiology of PTSD.