Oscar George Theodore Sonneck (1858–1928) was an influential American musicologist and composer, primarily associated with the genres of classical music and American folk music. Born in Germany, Sonneck emigrated to the United States in 1884, where he became a pivotal figure in the study and promotion of American music. Notable for his work as the first head of the Music Division at the Library of Congress, Sonneck played a crucial role in cataloging and preserving American musical heritage. He published significant research, including "The Music of the United States" and "The American Musicological Society," which helped lay the groundwork for future musicological studies. Sonneck's impact on music extended beyond academia; he advocated for the recognition of American composers and folk traditions during a time when European music was overwhelmingly dominant. His efforts contributed to a growing appreciation for American musical identity, influencing subsequent generations of musicians and scholars. His legacy endures through the promotion of American music's cultural significance and the establishment of musicology as a respected discipline in the United States.