This study examined the contribution of premilitary, military, and postmilitary risk factors to posttraumatic stress disorder (PTSD) and other postwar diagnoses in a sample of Vietnam veterans. PTSD was explained primarily by war stressors, including threat to life and exposure to grotesque death, but premilitary and postmilitary factors also contributed to the likelihood of a current diagnosis of PTSD. Panic disorder was also highly predicted by war experiences, whereas prewar functioning played a stronger role in several non-PTSD diagnoses. The study supported the notion that PTSD is specifically linked to intense stressors. Mechanisms for interactions among risk factors are discussed.