*The Concept of Model* is the first of Alain Badiou’s early books to be translated fully into English. With this publication English readers finally have access to a crucial work by one of the world’s greatest living philosophers. Written on the eve of the events of May 1968, *The Concept of Model* provides a solid mathematical basis for a rationalist materialism. Badiou’s concept of model distinguishes itself from both logical positivism and empiricism by introducing a new form of break into the hitherto implicated realms of science and ideology, and establishing a new way to understand their disjunctive relation. Readers coming to Badiou for the first time will be struck by the clarity and force of his presentation, and the key place that *The Concept of Model* enjoys in the overall development of Badiou’s thought will enable readers already familiar with his work to discern the lineaments of his later radical developments. This translation is accompanied by a stunning new interview with Badiou in which he elaborates on the connections between his early and most recent thought.