As the introduction to this book suggests, the management of international relations is inseparable from the subject of international organization. This has been evident especially since 1919 when reflections on the dangers of an almost pure nation-state system after World War I led to the creation of the League of Nations. Yet its inability to prevent World War II (WWII) did not lead to the abandonment of the effort to better organize international relations but rather to improving international governance. The resulting United Nations system from 1945, supplemented especially by regional organizations, again tried to restrain in particular the excesses of national psychology and power. While the UN has lasted longer than the League, it and other contemporary international organizations struggle to manage destructive nationalist views and power maneuvers. The process is complicated by certain sub-national actors, some with economic global range such as Royal Dutch Shell or with transnational political goals such as the Islamic State.