A former student of the Pratt Institute, Brooklyn, and the Académie Julian, Paris, in 1954 Thomas Downing enrolled at Catholic University, Washington, to study under Kenneth Noland. Noland, who became a significant influence on Downing's art, was one of the founders of the Washington Color Field Movement.
In the late 1950s, Downing shared a studio with Howard Mehring, another artist of the Washington Color School. In 1964 Clement Greenberg included Noland, Mehring, and Downing in Post-painterly Abstraction, an exhibition he curated for the Los Angeles County Museum of Art in 1964, in which Greenberg brought together exponents of what he saw as a new movement in painting that derived from the abstract expressionism of the 1940s and 1950s but "favored openness or clarity" rather than density. Other artists of note in this exhibition included Sam Francis, Gene Davis, Helen Frankenthaler, Ellsworth Kelly, Sam Gilliam and Morris Louis.
The Washington Color School became an umbrella term for a form of image making concerned primarily with color field painting, a form of non-objective or non-representational art that explored ways to use large solid areas of paint. The Washington Color School originally consisted of a group of painters who showed works in the exhibition "Washington Color Painters" at the now-defunct Washington Gallery of Modern Art in Washington from June 25 to September 5, 1965. The exhibition's organizer was Gerald Nordland and the painters who exhibited were Sam Francis, Gene Davis, Morris Louis, Kenneth Noland, Howard Mehring, Thomas "Tom" Downing, and Paul Reed. This exhibition, which subsequently traveled to several other venues in the United States, including the Walker Art Center, solidified Washington's place in the national movement and defined what is now considered the city's signature art movement.
Downing's work was included in the seminal The Responsive Eye exhibition at MoMA in 1965, as well as Systemic Painting at the Guggenheim in 1966, and Optic Nerve at Columbus Museum of Art in 2007.
A notable pupil of Downing's was the African-American color field painter Sam Gilliam.
"(Tom) was one of the first persons that ... let me know that the Washington Color School painting wasn't about what was being written by Greenberg. ... Tom would interestingly tell you that it was only about seeing; and then later he would tell you that it was only about color; or that it was only about the music of color; or the way you could structure color. And then later he would say that it was like pop art."
- Sam Gilliam
Works by Thomas Downing are included in the following public collections:
Philadelphia Museum of Art, Philadelphia
Wadsworth Atheneum, Hartford, Connecticut
Whitney Museum, New York
Museum of Modern Art, New York
Smithsonian American Art Museum, Washington, D.C.
San Francisco Museum of Modern Art, San Francisco
Federal Reserve Board of Governors, D.C.
Walker Art Center, Minneapolis
Virginia Museum of Fine Arts, Richmond
Norton Simon Museum, Pasadena, California
Oklahoma City Museum of Art, Oklahoma
The Phillips Collection, Washington, D.C.
The Museum of Fine Arts, Houston, Texas
Stanford University Museum and Art Gallery, Stanford, California
Dimock Gallery, George Washington University, Washington, D.C.
University of the District of Columbia Collection, Washington, D.C.
Board of Governors, Federal Reserve System, Washington, D.C.
The Baltimore Museum of Art, Baltimore
University of Virginia Art Museum, Charlottesville
Museum of Fine Arts, Boston, Massachusetts
Hirshhorn Museum and Sculpture Garden, Washington, D.C.
Georgetown University Collection, Washington, D.C.
Birmingham Museum of Art, Birmingham, Alabama
Provincetown Art Association and Museum, Provincetown, Massachusetts
Corcoran Gallery of Art, Washington, D.C
Solomon R. Guggenheim Museum, New York
Chrysler Museum of Art, Norfolk, Virginia
Denver Art Museum
Phoenix Art Museum
National Museum of American Art, Washington, D.C.
Metropolitan Museum and Art Center, Coral Gables, Florida
University Art Museum, Berkeley, California
Sunrise Museums, Charleston, West Virginia
The Mint Museum of Art, Charlotte, North Carolina
Georges Washington University Collection, Washington.D.C.
La Jolla Museum of Contemporary Art, La Jolla
Delaware Art Museum, Wilmington
Spartanburg Art Museum, South Carolina
Portland Art Museum
The Kreeger Museum, Washington, D.C