That the international system has changed dramatically in the years since the end of the Cold War has become a commonplace. But which changes are most profound, and what is their significance for international legal order? The last decade of the twentieth century generated dozens of books and articles hailing a transformed world order and interpreting its political, economic, and social consequences. We have more distance now. The first years of this century have underscored the significance of changes in the structure of international affairs – but they also demonstrate how difficult it is to interpret them with confidence.