This edited volume provides a comprehensive and critical review of what we know about military service and the life course, what we don't know, and what we need to do to better understand the role of military service in shaping people's lives. It demonstrates that the military, like colleges and prisons, is a key social institution that engages individuals in early adulthood and shapes processes of cumulative (dis)advantage over the life course. The chapters provide topical synthesizes of the vast but diffuse research literatures on military service and the life course, while the volume as a whole helps to set the agenda for the next generation of data collection and scholarship. Chapter authors pay particular attention to how the military has changed over time; how experiences of military service vary across cohorts and persons with different characteristics; how military service affects the lives of service members' spouses, children, and families; and the linkages between research and policy.