Others in the NY circle gave him advice. At the time of his first solo show, Barnett Newman sent him a letter of congratulations.His friendships with Newman and Mark Rothko placed him at the intellectual center of the Abstract Expressionist movement, but like de Kooning, Arshile Gorky and Franz Kline, Sills believed that it was not necessary to explain his art; he painted what he felt and it came from within.
Sills began his work as a fine artist when he was in his mid-thirties, about the time he married the mosaicist Jeanne Reynal. Essentially self-taught and inspired by Reynal's collection of abstract art, he began working with the materials he found in her mosaic studio, but soon branched out to oil on wood as well as canvas.
Sills's regular presence in the art world of the 1950s through the early 1970s as an African-American painter situated him as an integral element of the mainstream and African-American art. Thomas Sills perceived his art to be beyond the political. He found in Art a form of expression for the dynamism that escapes any formal constraints. Sills' work was highly intuitive and he too sought inspiration from primitive art—in the 1950s he made frequent trips to Mexico to study the sculptures, frescos and architecture of Chiapas and the Yucatan.
At the peak of his career in the 1960s and 1970s, his work was widely shown in museums. He had four solo shows at Betty Parsons Gallery, was regularly featured in art journals and is in museum collections. Today, there is a renaissance of the popularity of his works. He is being exhibited in many shows, most recently African American Abstract Masters at the Anita Shapolsky Gallery, New York and Abstraction Plus Abstraction at Wilmer Jennings Gallery at Kenkeleba, and Encore, Five Abstract Expressionists at Sidney Mishkin Gallery of Baruch College, The City University of New York in 2006.Wikipedia