The Western liberal tradition rests on free markets, limited government, human rights, and the rule of law. But as Jahn notes, those concepts originated as guides to the organization of domestic politics, and the effort to project them onto the international system, which began in the early nineteenth century, has been marked by tensions, dilemmas, tradeoffs, and contradictions. Liberal internationalism enshrines the norms of sovereignty and self-determination, for example, but it also has provided the rationale for imperialism, military interventionism, and postwar European efforts to transcend the sovereign state. In this rare and welcome survey of an important school of thought, Jahn argues that the tensions between the theory and the practice of liberal internationalism have been particularly pronounced since the end of the Cold War. During the past three decades, financial crises, the rise of illiberal democracy, and the hegemonic exceptionalism of liberalism’s most powerful advocate, the United States, have called into question the viability of a stable and universal liberal system. Jahn’s outlook is pessimistic, but her book nonetheless reaffirms why liberalism has endured thus far: the possible alternatives to a messy and incomplete liberal international order are all much worse.