This chapterexamines the history of the transitional decade between the 1920s and the 1930s, which saw the shift from sound in silent film performance practices to music in the soundtrack of the sound film. It traces the specific stages of this transition, focusing on music’s passage into the soundtrack, and suggests that sound film markedly transformed nearly every facet of filmmaking. It also argues that there are continuities in the treatment of music that have important impacts on the integrated soundtrack of the classical Hollywood sound film, which served as the benchmark for sound feature films generally.