The liberal order is decaying. Will it survive, and if not, what will replace it? On the eightieth anniversary of the publication of E.H. Carr's The Twenty Years' Crisis, 1919-1939, Philip Cunliffe revisits this classic text, juxtaposing its claims with contemporary debates on the rise and fall of the liberal international order. The New Twenty Years' Crisis reveals that the liberal international order experienced a twenty-year cycle of decline from 1999 to 2019. In contrast to claims that the order has been undermined by authoritarian challengers, Cunliffe argues that the primary drivers of the crisis are internal. He shows that the heavily ideological international relations theory that has developed since the end of the Cold War is clouded by utopianism, replacing analysis with aspiration and expressing the interests of power rather than explaining its functioning. As a result, a growing tendency to discount political alternatives has made us less able to adapt to political change. In search of a solution, this book argues that breaking through the current impasse will require not only dissolving the new forms of utopianism, but also pushing past the fear that the twenty-first century will repeat the mistakes of the twentieth. Only then can we finally escape the twenty years' crisis. By reflecting on Carr's foundational work, The New Twenty Years' Crisis offers an opportunity to take stock of the current state of international order and international relations theory.