Composer William Bolcom (1938-) has shown a remarkable capacity for incorporating disparate materials and combining them to create original compositions, while often using traditional genres and forms. This style has earned Bolcom the reputation as a leading composer of American postmodernism. This study provides a brief sketch of Bolcom's development as a postmodern composer, his repertoire for violoncello and piano, and it examines his compositional style as applied in his Sonata for Violoncello and Piano (1989). In the Sonata Bolcom applies a wide variety of musical vocabulary from serious and popular traditions. He juxtaposes contrasting ideas to create and resolve rhythmic, melodic and harmonic tensions and amalgamates concepts of three centuries of music history into one new integral work. All these disparate elements with classical, romantic, impressionist, expressionist, modernist and popular connotations are molded together to form a serious piece of musi c with a sense of humor. The three contrasting movements of the Sonata share many common rhythmic, melodic and harmonic traits. The movements form a congruent work of Classical and Romantic spirit, often reminiscent of Brahms' music, despite the mixed use of traditional, popular, and modernist musical languages.