Abstract: This dissertation examines the American reception of Gustav Mahler and Charles Ives between 1911 and 1965. During this period, both composers moved from a marginal position in the musical life of the United States to canonical status. To account for this shift, I examine the relationship between discourse about Ives and Mahler and the constellations of ideas that grew out of several major episodes in American intellectual history: the social reform movements of the Progressive Era, the emergence of the Greenwich Village intellectuals, the influx of Central European émigrés who sought refuge from Hitler, the ascendancy of psychoanalysis in the United States, and the formation of the anti-communist left during the Cold War. Beyond providing a nuanced reception history of Ives and Mahler, my dissertation is intended to be a case study of the kind of work that can be done at the interstices between musicology and American intellectual history. While Mahler and Ives achieved canonical status at roughly the same time, I show that they found differing support en route. From the late twenties, American modernists championed Ives as the embodiment of a distinctively American ethos. Mahler's promoters were more diverse, consisting of European conductors who spent the concert season in the United States, orchestral musicians, amateur enthusiasts, and a handful of critics. Accordingly, Mahler was subjected to a variety of interpretations, his music being seen by turns as a vehicle for forging a progressive unity, a psychoanalytical case study, and either a comment on or a consequence of modernity. With the onset of the Cold War, the meanings ascribed to the music of Mahler and Ives shifted, as their constituencies converged and expanded. Crucial to these new interpretations, I argue, was a complex of ideas about the opposition between liberal democracy and totalitarianism. Ives was held up as a paragon of the autonomous man, and his commitment to transcendentalism moved to the foreground. Simultaneously, Mahler was celebrated for giving musical embodiment to the tensions, contradictions, and conflicts of life---those things that totalitarian regimes sought to resolve through the forceful imposition of ideology.