What characterized conservatory music theory pedagogy in nineteenth-century Europe? This article discusses the traditions of music theory pedagogy associated with the conservatories in Paris, Vienna, and Leipzig, specifically focusing on the middle of the nineteenth century (ca. 1830–70). In the first section, the characteristics of the three individual traditions are discussed separately. The second section compares these traditions from three perspectives: theoretical framework, pedagogical approach, and historical legacy. Although the traditions are different on several central points (e.g., ties to Italian partimento pedagogy in Paris, to Ramellian fundamental bass in Vienna, and to Weberian Roman numeral analysis in Leipzig), they also have some fundamental similarities that drew the borders—the defining limits—of conservatory music theory. The author argues that in the nineteenth century the idea of music theory as a primarily written discipline (centered on textbooks and written exercises and largely separated from musical performance) became a central element of these general characteristics of music theory pedagogy that would be taken for granted and accepted as self-evident across institutional traditions.