The accordion, a little known instrument in the world of serious or art music, does possess enormous capacities for artistic expression of the highest order.In the twentieth-century, some accordionists began to realize the instrument's potential. These accordionists made transcriptions of the classical repertoire, composed original works for the instrument, and formed the American Accordionists' Association to encourage, among other things, the advancement of the instrument by commissioning leading twentieth-century composers to write for the instrument.This study thus proposes to examine a select group of works for solo accordion and varying types of accompanying ensemble, by twentieth-century American composers. Each work has been critically analyzed and evaluated in an attempt to see what impact, if any, such works have had on the world of serious music in general.The study analyzes and evaluates ten works for accordion and accompanying ensemble including: Henry Cowell's, Concerto Brevis for Accordion and Orchestra; Paul Creston's, Concerto for Accordion and Orchestra; David Diamond's, Night Music for Accordion and String uartet, Ftoy Harris', Theme and Variations for Solo Accordion and Orchestra; Alan Hovhaness', Accordion Concerto, op. 174, and Rubaiyt, Op. 282 for narrator, accordion, and orchestra; William Schimmel's, Concerto for Three (accordion, bass viol, and percussion); Eugene Zador's, Concerto for Accordion, Strings, and Orchestra; and George Zorko'p, On-Gaurd for accordion and chamber. ensemble. There is a comparison of these works to others of a similar nature by the composer to see if he altered his style in any substantive way to accommodate the accordion.While it may be disappointing to discover that the efforts to date have not resulted in any masterpieces that transcend the medium, the accordion is only now approaching maturity in terms of technical and artistic achievement. There is considerable evidence of concern, interest, and creative energy being spent on the part of many on behalf of the accordion, which at least offers promise of significant results in the relatively near future.