Posttraumatic stress disorder (PTSD) is the most prevalent psychological disorder experienced by Vietnam veterans. However, there are many other disorders and problems of adjustment, like social anxiety and social phobia, that have not been fully investigated in this population. This study examined the prevalence of social phobia and the comorbidity of social phobia and PTSD, and tested out a theory of the etiology of social anxiety in trauma victims. Forty one Vietnam combat veterans were interviewed and completed self-report measures assessing PTSD and social phobia. Adversity of homecoming was also assessed. Using a conservative multi-method assessment approach, 32% of the sample were found to be positive for both social phobia and PTSD. Veterans with PTSD were significantly more likely to carry an additional diagnosis of social phobia as compared to veterans without PTSD. Adversity of homecoming and shame about one's experience in Vietnam were significant predictors of current level of social anxiety over and above the effects of pre-military anxiety and severity of combat exposure. These observations suggest that social anxiety and social phobia may be significant problems among individuals with PTSD. Further, these findings offer preliminary support for the theory that posttrauma environment may impact upon the later development of social anxiety.