Draft lottery number assignment during the Vietnam Era provides a natural experiment to examine the effects of military service on crime. Using exact dates of birth for inmates in state and federal prisons in 1979, 1986, and 1991, we find that draft eligibility increases incarceration for violent crimes but decreases incarceration for nonviolent crimes among whites. This is particularly evident in 1979, where two‐sample instrumental variable estimates indicate that military service increases the probability of incarceration for a violent crime by 0.34 percentage points and decreases the probability of incarceration for a nonviolent crime by 0.30 percentage points. We conduct two falsification tests, one that applies each of the three binding lotteries to unaffected cohorts and another that considers the effects of lotteries that were not used to draft servicemen. (JEL K42, H56)