Around the world, populist parties have sprung up in formerly and formally liberal-democratic polities, challenging their existing political parties and leaders, and frequently overwhelming them. These challenges and successes were rarely predicted, arriving so soon after the wave of liberal democratic and constitutional enthusiasms, proclamations and institution-building which peaked in the 1990s. Bringing together scholars from law, political science and philosophy, this collection explores the character of contemporary populisms and their relationships to constitutional democracy. With contributors from around the world, it offers a diverse range of nuanced perspectives on populism as a global phenomenon. Using comparative and multi-disciplinary techniques, this book considers the specifics and similarities of populisms, and raises general questions about their nature and potential futures.