A growing amount of literature has documented differences between United States (US) veterans of the armed services and civilians in mental and physical health outcomes. However, less is known about the correlates of these outcomes, and most studies have used samples of veterans receiving US Department of Veteran's Affairs (VA) healthcare only. Using a nationally recruited sample from the Midlife in the United States (MIDUS) II study, we examined stress exposure, mental health symptoms, and common vulnerability factors (inflammation, trauma history, emotion regulation) across veterans and civilians. The present study included data from the baseline psychosocial timepoint (Project 1), the Milwaukee subsample (n = 4,633), and the biomarker study (Project 4; n = 1,099). We found that veterans reported greater stressful and traumatic life events but fewer mental health symptoms compared to civilians. Further, analyses suggested some differences based on a history of combat or probability of using VA healthcare, with higher levels of depression among combat veterans and more head injury among those likely to use VA healthcare. Results suggest some variability in inflammatory markers but few differences in emotion regulation or health characteristics. The present study was limited by minimal available data on military service. Future research is needed on veterans outside of VA healthcare, with attention to characteristics such as the branch of service, rank, and unit cohesion. The goal of this line of research is to better understand factors that may be addressed in prevention and intervention efforts in service of best caring for those who have sacrificed for military service.