The Sonata for Flute, Viola, and Harp, written in 1915, is an excellent example of Claude Debussy's later style. The purpose of this thesis is to discuss the elements of this later style and represent them graphically. In particular, the intermovemental motives, both harmonic and melodic, and the manipulation and development of the phrases are closely examined. Also discussed is the impact of the interaction, and orchestration, and equal use of the three instruments on the effectiveness of the piece. Upon study of the analysis and the accompanying discussion, one will have a greater understanding of the individual parts which together make up a unique and fascinating whole; one of Debussy's finest compositions.