The neo-classic movement in Italy, which gained momentum in the early 1920's, was rooted in an instrumental style patterned after that of the Baroque era. The term "new classicism," proposed by Ferruccio Busoni in 1920, represented a reaction against the extreme chromaticism and large performance forces of the late nineteenth century. The pianistcomposer Alfredo Casella, after earlier periods in which he was influenced by such diverse composers as Mahler, Debussy, and Schoenberg, soon became the chief spokesman for the neoclassic movement in Italy. Casella considered the Sinfonia, Arioso and Toccata his most important work for the piano, because of its size and musical content. It is notable for its usage of thematic transformation, much of which is based on the interval of a fourth or fifth. This study includes a formal outline of each movement, showing sectional divisions and tonal regions, as well as illustrations of thematic transformation and intervallic patterns. Also discussed are the work's neoclassic style characteristics, including counterpoint, pandiatonicism, modality, and linear cadential treatment.