I am grateful for comments on an earlier draft by Erin Graham, Alex Thompson, Alex Wendt, Sara Brooks, Jennifer Mitzen and Randy Schweller. I would particularly like to thank the organizers of the conference at METU for their comments and invitation to come to Ankara, specifically: Dean Eyüp Özveren, Chair Meliha Altunisik and Professor Faruk Yalvaç. I am also grateful to Daniele Archibugi, Nils Gleditsch, Mahmood Monshipouri, Julian Saurin and other participants who offered critique and advice.The international system has profoundly changed since the end of World War II. The number of states has multiplied more than fourfold while empires have receded into the past. From one vantage point this is the heyday of a system of sovereign states. The system is structurally anarchic.