This volume situates the work of American poet Charles Olson (1910-1970) at the centre of the early post-war American avant-garde. It shows Olson to have been one of the major advocates and theorists of American modernism in the late 1940s and early 1950s; a poet who responded fully and variously to the political, ethical, and aesthetic urgencies driving innovation across contemporary American art. Reading Olson's work alongside that of contemporaries associated with the New York Schools of painting and music (as well as the exiled Frankfurt School), the book draws on Olson's published and unpublished writings to establish an original account of early post-war American modernism. The development of Olson's work is seen to illustrate two primary drivers of formal innovation in the period: the evolution of a new model of political action pivoting around the radical individual and, relatedly, a powerful new critique of instrumental reason and the Enlightenment tradition. Drawing on extensive archival research and featuring readings of a wide range of artists including, prominently, Barnett Newman, Mark Rothko, David Smith, Wolfgang Paalen, and John Cage, Charles Olson and American Modernism offers a new reading of a major American poet and an original account of the emergence of post-war American modernism.