John Williams has been associated with the sound of Classical Hollywood Cinema (1933–58) since his popular neoclassical scores of the 1970s seemed to revive the central European tradition represented by composers such as Max Steiner and Erich Wolfgang Korngold (among others). Alongside this popular European romantic style, however, Williams’s scores often reference a diverse array of American musical idioms. When scoring American-centric narratives, or specific genres, Williams seems to rely on three distinct idioms, each with their own specific histories and associations both within and outside of their films. For westerns (The Cowboys), Coplandesque pastoralism serves to glorify landscape and maintain a myth of the West in ways reminiscent of Copland’s ballets of the 1940s. For political dramas (JFK) or war epics (The Patriot) the use of dignified brass fanfares, marches, and calls summon metatextual links to ceremony and the military to endow images with an earnestness and a patriotic air. In historical dramas (Lincoln) a hymn-inspired vocabulary generates a sense of the reverential or noble. Taken together, these idioms form a lingua franca of American-associated sounds, demonstrating how Williams cultivates the musical legacies and traditions of his homeland, while referencing European compositional practices. Three chapters investigate the histories of each of these idioms and their manifestations across a selection of Williams-scored films. By tracing the lineage of each idiom, exemplifying their associative rigidity, and revealing how Williams adapts them, this thesis not only showcases Williams’s own nationalistic mode, but additionally highlights issues arising from the pervasiveness of this style in a broader Hollywood context.