In One and Five Ideas eminent critic, historian, and former member of the Art & Language collective Terry Smith explores the artistic, philosophical, political, and geographical dimensions of Conceptual Art and conceptualism. These four essays and a conversation with Mary Kelly—published between 1974 and 2012—contain Smith's most essential work on Conceptual Art and his argument that conceptualism was key to the historical transition from modern to contemporary art. Nothing less than a distinctive theory of Conceptual and contemporary art, One and Five Ideas showcases the critical voice of one of the major art theorists of our time.