We examine hypotheses involving the potential health advantages of selection into military service and the potential health disadvantages associated with the experience of military service by comparing later-life mortality rates for veterans and nonveterans as well as among veterans based on their cohort of reentry into civilian life. We use data on 3,453 men, including 1,496 veterans from the older men cohort of the National Longitudinal Surveys to estimate Cox proportional hazard mortality models. We distinguish between veterans and nonveterans and further classify veterans by age at exit while incorporating measures associated with military selection, health behaviors, and socioeconomic status. Veterans who were discharged from the military at older ages have a mortality advantage relative to veterans discharged at younger ages. For the 1914-1921 birth cohorts, the mortality advantage for veterans who exited around age 30 is apparent for deaths before age 65, but rates equalize across all groups when deaths at older ages are included. These findings are robust to the inclusion of background characteristics, education, occupation, body mass index, smoking, marital status, and proxies for service deferments. Rather than focusing on a general health effect of military service, per se, future research should distinguish among individual traits; the nature, timing, and duration of exposures relative to life course stage; and the sociohistorical context of military service to expand our understanding of the differential health consequences of military service.