Harmonielehre is a forty-minute orchestral composition by the American composer John Adams, composed in 1985. In his memoir, Adams stated that the piece "was a statement of belief in the power of tonality at a time when I was uncertain about its future" and that it was "a one-of-kind [sic] once-only essay in the wedding of fin-de-siècle chromatic harmony with the rhythmic and formal procedures of Minimalism".