Composers of piano music in the first half of the twentieth century challenged the musical conventions of the previous century. Employing elements of their national traditions, they experimented with rhythm, tonality, texture and form. The sonata format, in particular, provided composers with an infinite variety of creative approaches. The solo keyboard sonata developed in the Classical era and continued to interest composers during the 19th century. In the 20th-century it became a flexible tool for exploring the thematic process, modulation and many other elements. The 20th-century piano sonata is well-suited for this dissertation project. The works selected-among the most substantial in the repertoire--demand the most from the performer in terms of analysis, technique and aesthetics. Further, Charles Ives' Piano Sonata No.2, Concord, Mass., 1840--60 is seldom heard in concert. This Dissertation comprises three piano recitals that showcase piano works by Debussy, Copland, Prokofiev, Ravel, Bartok, Berg, Barber, and Ives. The performances took place in 2008 and 2010 in Gi1denhom Recital Hall of the Clarice Smith Performing Arts Center, and in 2011 in Ulrich Concert Hall at the University of Maryland. The recordings are documented on compact discs that are housed within the University of Maryland Library System.