This book explores the post-national defense and its gender implications. A characteristic of the post-national defense is that less attention is paid to the defense of the territory and more to the security situation outside its borders, often in cooperation with other states. It is exemplified with Sweden and the EU as empirical cases. The main research question is how gender aspects and UN SCR 1325 has influenced the way that the post-national defense organizes its practices and the policies pursued? A feminist constructivist institutional approach is the theoretical base. By combining theories on gender, masculinity, militarism, and cosmopolitanism in rich case studies it improves the theory’s complexity and shows its applicability. UN SCR 1325 has been integrated in training and education of the troops of the post-national defense. Gender has been mainstreamed in post-national military practice but at the same time re-interpreted as meaning women, often also women in distant places. This book also shows how militaries have used (hetero)sexuality as an important resource in combat effectiveness. This is a challenge for the post-national defense that engages in peace tasks because military organizations have the use of weapons and violence as its core professional skills. Furthermore, this military training has been tightly connected with masculinity. When gender is equated with women it becomes difficult to raise issues about masculinity, violence and sexuality, an equally important aspect in a gender analysis of the post-national defense.