Women have never been exempt from war. Their roles have included providing justification for war, as well as serving as victim, support, and warrior. In general, women have been more active when conflict has occurred in their homeland, whether in a defensive war, a war for independence, or a civil war. Also, their numbers have tended to be larger in irregular or insurgent forces than in forces in which the enlisted are trained and commanded by a well-established government. In recent years, however, even in the latter, women have become more numerous and their assignments more varied. Two factors contributing to this have been stronger norms against sex discrimination and the end of conscription. This essay discusses the American experience to illuminate reasons given for limiting women’s military service; the changes in women’s military participation since World War II, especially since 1972; and the experience of women now serving in uniform.