This volume advances the research agenda of one of the most remarkable political thinkers of our time: Jon Elster. With an impressive list of contributors, it features studies in five topics in political and social theory: rationality and collective action, political and social norms, democracy and constitution making, transitional justice, and the explanation of social behavior. Additionally, this volume includes chapters on the development of Elster's thinking over the past decades. Like Elster's own writings, the essays in this collection are problem-driven, non-ideal inquiries of practical relevance. This volume closes with lucid comments by Jon Elster.