Part One of this project examines a group of piano pieces that bear the title sonata-fantasy or fantasy-sonata. While much has been written about quasi-sonata fantasies and quasi-fantasies of the Romantic period, the sonata/fantasy hybrid works of the following era have largely been a neglected area in music research. The purpose of this document is to fill this void and provide an introductory study of these works. The introductory chapter includes a list of sonata-fantasies and fantasy-sonatas I have found in U.S. libraries. The next two chapters outline the history of the fantasy as a genre and its relationship to the sonata up to the mid-nineteenth century: while the two were generally viewed as two contrasting genres in the eighteenth century, their boundaries gradually began to disappear in the early nineteenth century. Six works selected for detailed analysis in this project are Joachim Raffs Fantasie-Sonate, op.168; Alexander Scriabins Sonate Fantaisie, op.posth. and Sonata No.2 (Sonate-Fantaisie), op.19; Joaquin Turinas Sonata Fantasia, op.59; Anatoly Nikolayevich Aleksandrovs Piano Sonata No.11 Sonata Fantasia, op.81; and George Rochbergs Sonata-Fantasia. The final chapter summarizes the analyses of the selected works and explores explanations for the emergence of pieces bearing the sonata/fantasy compound titles. Part Two of this project consists of program notes for the repertoire used in fulfilling the performance requirements of the D.M.A. degree. The following works are individually discussed in this section: Piano Trio No. 28 in D Major, Hob. XV: 16 by Franz Joseph Haydn; Piano Trio in D Major, No. 70 no. 1, Ghost by Ludwig van Beethoven; Piano Trio No. 2 in C Minor, op.66 by Felix Mendelssohn; Prelude in D Major, BWV925 by Wilhelm Friedmann Bach(?); Sonata in G Major, op.78 (D.894) by Franz Schubert; Klavierstcke, op.118 by Johannes Brahms; Rain Tree Sketch for piano (1982) by Toru Takemitsu; Los Requiebros by Enrique Granados; and Concerto in G Major for Piano and Orchestra by Maurice Ravel.