A description is presented of the results of the first phase of a programmatic research effort into the incidence and etiology of Post-Traumatic Stress Disorder (PTSD) among noncivilian Vietnam and Vietnam-Era veterans. Questionnaire data were collected from 238 Vietnam veterans and 85 Vietnam-Era veterans stationed at a moderate-sized U.S. Army post on the East Coast in the Spring of 1982. Results show a significantly lower incidence of PTSD than has been reported in the literature among civilian Vietnam veterans. Social support received during the first year back from Vietnam appears to contribute more to the attenuation of PTSD symptomatology than does combat experience alone. Additional results highlight the relationship between physical and psychosocial health.