Given the wars in Iraq and Afghanistan, there is considerable interest in understanding the consequences of military service for a variety of outcomes. This interest is not new. In the past, researchers have studied the eff ects of service on later-life mortality (e.g., Hearst, Newman, and Hulley 1986; London and Wilmoth 2006; McDonagh 1946; see also MacLean, Chapter 10 of this volume), marital behavior (e.g., Call and Teachman 1996; Laufer and Gallops 1985; Pavalko and Elder 1990; see also Burland and Lundquist, Chapter 8 of this volume), and economic well-being (e.g., Angrist 1990, 1991, Angrist and Krueger 1994; see also Kleykamp, Chapter 7 of this volume), as well as on other outcomes. Although researchers have made important advances in our understanding of the consequences of military service in a variety of contexts, these studies are generally plagued by one or more methodological problems. Many of those same methodological problems would, as well, confront researchers attempting to advance the agenda for future research on military service (see Teachman, Chapter 14 of this volume).