Don Gillis wrote Symphony No. 5½ (1947) in order to reconcile the American public with modern art music. By synthesizing jazz (as well as other American folk idioms), singable melodies, and humor, and then couching them into symphonic language, Gillis produced a work that lay listeners could process and enjoy. The piece was an immediate success and was played by orchestras across the globe, but it did not retain this popularity and it eventually faded from relevancy. This study focuses on elements that contributed to the initial efficacy and ultimate decline of the work. Due to its pervasive popular influences, Symphony No. 5½ is a crystallized representation of time in which it was written, and it soon became dated. Don Gillis did not harbor the idea that Symphony No. 5½ would grant him great wealth or musical immortality; he had a more pragmatic goal in mind. He used every musical element at his disposal to write a symphonic work that would communicate directly with the American people via a musical language they would understand. He was successful in this regard, but the dialogue ended soon after mid-century.