During Aaron Copland's long and productive life, he has written many compositions of distinction; among his piano compositions are the Passacaglia, Piano Variations, and Four Piano Blues. These three piano works were composed during a span of over twenty years and reflect many different influences in the composer's musical life. The Passacaglia, an early work, was written under the direction of Copland's teacher, Nadia Boulanger. It was strongly influenced by her and the French neoclassic school. The influence of jazz is most prominent in the Four Piano Blues, whereas the Piano Variations were influenced by Arnold Schoenberg and other composers of the twelve-tone school. This study contains an examination of each of three piano pieces mentioned, with emphasis upon aspects of thematic development, harmony, rhythm, and sonority; then a comparison between the pieces is made.