The music of John Adams (b. 1947) exemplifies a reinvestment in traditional instrumental genres and musical values that began to take place in contemporary music in the late 1970s and early '80s. His Harmonielehre for orchestra (1984-85) meets many of the conditions of the symphonic genre, including its scoring for full orchestral forces, its multi-movement structure, its presentation of contrary, dialectical melodic gestures, and its dramatic thematic and harmonic conflict. It is thus ironic that Adams would title his composition after a treatise written by Arnold Schoenberg, a figure whose break from the musical past inspired many of the complex and experimental musical models that arose between the publication of his own Harmonielehre (1911, rev. 1922) and that of Adams. But to conclude that Adams' composition is a statement about tonality is perhaps over-simplistic. Examination of the two works reveals more similarities between the composers' artistic philosophies than differences. This dissertation is an attempt to expose these similarities in order to discover the motivations behind Adams' curious decision to title his composition after Schoenberg's treatise, and to gain a deeper understanding of the artistic priorities shared by both composers that arises from the interrelationship between their respective Harmonielehren. Adams' title is partly a marker of the types of Romantic-era stylizations that pervade his score. But I argue that the relationship between the two Harmonielehren is not merely cursory. Prevalent themes within Schoenberg's prose can inform the analysis and interpretation of Adams' composition. Adams draws on Schoenberg's treatise as a signifier of his creative identification, one that both complements and departs from the creative model presented in Schoenberg's text. Both Harmonielehren confront the aesthetic expectations of their individual times and places, but while Schoenberg centers his creative identification in a discourse of restless inquiry into new materials and models of musical expression, Adams seemingly subscribes to Schoenberg's presentation of composition as craft, as the working-with and fitting-together-of the pre-existing sound vocabularies of music.