This study evaluates the characteristics of the men who served in the volunteer military in combat occupations. It examines whether these characteristics stem from supply-side or demand-side decisions, or reflect class bias. The findings suggest that, on the supply side, men who had greater academic abilities were more likely to go to college, thereby avoiding military service and the possibility of serving in a combat occupation. On the demand side, the armed forces were more likely to exclude men with lower academic abilities but were more likely to assign such men in the military to combat occupations. Net of the impacts of these supply-side and demand-side decisions, men who served in combat occupations still differed from those who did not in terms of their family background. The impact of family background was stronger on entering the military than on being assigned to combat occupations once in the military.