Building on ideas first advanced by Arnold Schoenberg and later developed by Erwin Ratz, this book introduces a new theory of form for instrumental music in the classical style. The theory provides a broad set of principles and a comprehensive methodology for the analysis of classical form, from individual ideas, phrases, and themes to the large-scale organization of complete movements. It emphasizes the notion of formal function, that is, the specific role a given formal unit plays in the structural organization of a classical work.