In this groundbreaking book, Viola argues that all international systems contain two competing logics of order, pitting equality and inclusion against inequality and exclusion. The United Nations, the premier multilateral organization, enshrines the principle of sovereign equality. But other organizations, such as the International Monetary Fund and the World Bank, have differential voting quotas, and the Nuclear Nonproliferation Treaty formally divides the world into nuclear haves and have-nots. The book develops a “closure theory” to explain why the rules and institutions of the international system exhibit this mix of equality and inequality of rights and privileges. States have used both inclusion and exclusion to shape the global playing field. Those seeking to establish rules and institutions of global governance peddle universalist principles to attract other states. But more exclusive groupings of states—clubs—provide ways for states to assert dominance, define property rights, and control the flow and distribution of resources. Viola shows how the dynamics of inclusion and exclusion are linked and work together. The modern system of international relations may be both more open and more global than ever before, but it is also a bounded political space run by privileged members.