This open access book by Nils Karlson explores the strategies used by left- and right-wing populists to make populism intelligible, recognizable, and contestable. It presents a synthesized explanatory model for how populists promote autocratization through the deliberate polarization of society. It traces the ideational roots of the core populist ideas and shows that these ideas form a collectivistic identity politics. Karlson argues that to fight back requires the revival of liberalism itself by defending and developing the liberal institutions, the liberal spirit, liberal narratives, and liberal statecraft. The book also presents and discusses an extensive list of counterstrategies against populism. Written within the tradition of political theory and institutional economics, this book uses a wide variety of sources, including results and analyses from social psychology, ethics, law, and history.