Although music was a prominent—and sometimes inescapable—feature of international expositions ("world's fairs"), studies rarely address the sonic elements of these large public occasions. Instead, historians have focused on exposition architecture, advertisement, and exhibits. Music, however, played a significant role in shaping the experience of many expositions. Administrators allocated relatively large budgets for musical activities and scrupulously planned the musical programming. Newspaper and witness accounts attest to the ubiquity of musical performances in exhibit halls, exposition thoroughfares, specially designed concert halls, and amusement zones. Yet music was not just physically present on fairgrounds; it often stood at the center of heated disputes over national representation among administrators, critics, and audiences. This dissertation analyzes the musical activities of four international expositions held in Santiago de Chile, Philadelphia, Buenos Aires, and San Francisco between 1875 and 1915, the "golden age" of international expositions. Using an interdisciplinary approach that engages with research in history, cultural studies, and musicology, I have examined how exposition music contributed to representations of identity on fairgrounds, particularly along lines of gender, ethnicity, nationality, and class. I account for the wide variety of musical production that occurred in and around exposition grounds, including (but not limited to) the mainstream musical events sponsored by exposition administrators. As one might expect, heavily publicized mainstream musical events usually reinforced dominant social hierarchies by presenting the music of middle- and upper-class white men as evidence of human advancement. This dissertation, however, argues that groups marginalized by official exposition events—including women, American Indians, and middle-class Argentines—also saw music as a powerful means of representation, and sometimes used musical events to provide alternative representations of themselves. At Latin American expositions, organizers used musical events to situate their nations as full members of the international community, counteracting the marginalization and exoticization that they often faced at expositions held in the United States and Europe.