Combat experiences early in adulthood may have lifelong ramifications. In the Vietnam Era Twin Study of Aging (VETSA), the authors studied lifetime educational attainment (LEA) in 236 male twins from the Vietnam Era Twin Registry. Twins who served in Vietnam had completed significantly fewer years of education by their 50s. Level of combat exposure was negatively correlated with LEA. To control for variables that might confound the relationship between combat and LEA, the authors compared twin pairs discordant for Vietnam service ( n = 44 pairs); the twins who served in Vietnam had significantly lower LEA than their cotwins. Greater cognitive ability at military induction and older age at induction both predicted higher LEA, but after statistically controlling for these variables, the relationship between combat exposure and LEA remained significant. The VETSA results demonstrate that combat experience and entering military service at a younger age may reduce lifelong educational prospects, even after cognitive ability is controlled.