This article examines the relationship between Aaron Copland’s activities as composer and as pedagogue in order to illuminate the fraught midcentury relationship between musical modernism and middlebrow culture. I situate his unpublished lecture notes and music appreciation books within the middlebrow context and trace their connections with the works he composed during this period. At the center of my investigation is the contentious midcentury category of “style,” which implicated both Copland’s music and his pedagogy in ways that illuminate middlebrow cultural appreciation at large. Challenging long-standing modernist depictions of the middlebrow as the straightforward commercialization of high culture, I excavate characteristic middlebrow commitments to compromise, novelty, and breadth that proved even more unsettling to midcentury hierarchies than mass culture’s supposedly shameless pandering. By emphasizing Copland’s commitment to a canon of modern “styles,” in composition as in music appreciation, I draw out underlying tensions between his “middlebrow” approach to modern music and a “higher,” purer form imagined by Arnold Schoenberg and Theodor W. Adorno. At the same time, I show how these distinctions often threatened to collapse. On a broader methodological level, I chart a middle course between “social” conceptions of the middlebrow—as a means of marketing, distributing, and teaching high art to a mass audience—and “aesthetic” discussions of it as a compositional style. By examining the reciprocity between Copland’s pedagogy and music, I ultimately suggest that the problem which middlebrow culture posed to high modernism lay not just in its ability to mediate between high and low, modernism and mass culture, but also in the challenges it posed to fantasies of aesthetic immediacy and autonomy.