Lo, Pei-RongSonata forms, from binary and ternary to sonata-allegro, have been commonly used and seen as principal structures in instrumental music for centuries. Sonata- allegro form usually applies to a single movement, generally the first movement in a multi-movement work. Binary and ternary forms have also been used in individual free-standing works. In the early 18th-century binary and ternary forms combined to evolve into a one-movement musical composition which later developed into what came to be called sonata-allegro form. The principle of sonata-allegro form refers to a combination of thematic and key relationships which are more complex and variable than previous forms. Refinement of sonata forms started almost along with their introduction. Then, starting in the early 19th century, sonata-allegro form began to have larger and more complicated possibilities. Beethoven expanded it with his brilliant use of thematic structure and architectural sense. His instrumental sonatas became the model for sonatas in the Romantic period. After Beethoven, sonata-allegro form in the Romantic period varied widely in both structure and tonality, examples being found in the piano sonatas of Chopin and the instrumental sonatas of Richard Strauss. Sonata-allegro form in the 20th century came in countless varieties. It had a freer structure and could often be considered a variant of ternary form. The 20th-century Neo-classicists, for example, turned back to Baroque and Classical forms while using contemporary harmony, rhythm and even ethnic or nationalistic flavors. Many of these features can be seen in works such as the instrumental sonatas by Prokofiev and Poulenc. This performance dissertation consists of three recitals which were performed at the University of Maryland and is documented on compact disc recordings which are housed within the University of Maryland Library System. The recordings present the music of Richard Strauss, Poulenc, Chopin, Scarlatti, Prokofiev and Beethoven.en-USDissertation