The compositions to be considered in this study have been divided into three periods, corresponding with certain times in the life of Alfredo Casella. There is enough consistency of style in the compositions of each period to justify this division. The first period, characterized by lyricism and virtuosity, includes the works written in Paris after Casella left the Paris Conservatory. The second period, with its chromaticism and dissonance, comprises his output during the first years after his return to Italy. The third period begins with the close of World War I. In this period Casella returns to a classic style which is firmly embedded in an extended tonal system. The compositions of this period combine various ideas and styles gathered through the years and blend them into works marked by maturity, sincerity, and originality.