It seems today that a sense of crisis permeates international affairs. From war to pollution to trade and beyond, there is much talk of the disintegration of the settled ways of doing things and fear of what comes next. The twenty-first century has turned sour for many believers in international order. This is not unique in history; order has been on the minds of writers for centuries, from Kant to Carr to Hedley Bull. It is hard to find a period in history when there has not been some sense of crisis. The problem of international order is both a perennial theme and an urgent contemporary concern. The essays in this collection broaden the conversation to consider the ambiguity, complexity, and contradiction within the concept of world order. Order is neither self-evident nor universally agreed upon; to the contrary, it is contested, political, and contingent. Order is a very disorderly idea.