This study exploits the differential effects of the Vietnam War across birth cohorts to measure the effects of combat exposure on later violence and crime. Combat exposure and violent acts are measured using self-reports from the National Vietnam Veterans Readjustment Study. I find large positive effects on violence for blacks, suggestive evidence of positive effects on violence for whites and on arrests for certain offense types, and negative "incapacitation" effects on arrests during the men's years abroad. The estimates, while imprecise, suggest that the social cost of the violence and crimes caused by Vietnam-era combat exposure was roughly $65 billion. (Contains 4 figures, 7 tables, and 17 footnotes.)