Thomas was a graduate of Queens College in New York. During his years there, he joined the Umbra Workshop, which drew young writers to the Lower East Side of New York City in search of their artistic voices. It served as a crucible for emerging black poets, among them Ishmael Reed, David Henderson and Calvin C. Hernton. The workshop was one of the currents that fed the Black Arts Movement of the '60s and '70s, the first major African-American artistic movement after the Harlem Renaissance.
For more than two decades a professor of English at the University of Houston–Downtown, Thomas also made important contributions to the study of African-American literature. In 2000, he published Extraordinary Measures: Afrocentric Modernism and 20th-Century American Poetry, his overview of the work of James Fenton and Amiri Baraka, among others.