Thompson composed three symphonies and numerous vocal works including Americana, The Testament of Freedom, Frostiana, and The Peaceable Kingdom, inspired by Edward Hicks's painting.

Americana, a song cycle, is written in a 20th-century musical art style known as "News Items"—compositions that parody newspaper layout and content, or whose lyrics are lifted from media of the day.

[2] The song cycle's texts come from such publications as the Seattle, Washington, Post-Intelligencer, the Little Rock, Arkansas, Gazette, and a leaflet issued by the National Women's Christian Temperance Union.

In honor of Thompson's vast influence on male choral music, on May 2, 1964, he became the first recipient of the prestigious University of Pennsylvania Glee Club Award of Merit.

[3] Established in 1964, this award sought "to bring a declaration of appreciation to an individual each year that has made a significant contribution to the world of music and helped to create a climate in which our talents may find valid expression."