Posttraumatic stress disorder (PTSD) and social anxiety disorder (SAD) frequently co-occur. Preliminary data from treatment-seeking and veteran samples suggest that the impact of PTSD-SAD comorbidity may be additive, conferring distress and impairment beyond that of either disorder alone. The current study sought to clarify and extend existent research using wave 2 of the National Epidemiologic Survey of Alcohol and Related Conditions, an epidemiological sample of American adults. Individuals who met criteria for comorbid PTSD-SAD were compared to those with either disorder alone on measures of lifetime suicide attempts or quality of life as measured by the Medical Outcomes Study Questionnaire. Relative to those with either PTSD or SAD, individuals with comorbid PTSD-SAD demonstrated an elevated risk of lifetime suicide attempts and substantially lower levels of physical and mental quality of life. The psychosocial consequences of PTSD-SAD comorbidity are substantial. Patients may benefit from early interventions to remediate social distress and improve support networks before more intensive psychotherapeutic interventions.