By the time he was twenty, he was painting distinctively urban surrealism, while producing critically admired portraits, something he continued to do during his lifetime.
Around 1960, his UFO and Probe Series began to include controlled abstractions against hard edge geometric fields of colors.
In 1968, he had a joint exhibit with Mario Cooper at Lehigh University Art Gallery organized by Francis Quirk.
[2] At his premature death, he was setting expressionistic forms in a wide bands of colors, separated by a white field.
Essays about his work appear in Master Paintings from the Butler Museum, Catalog of the Whitney Collection, and in Permanent Collection of the Wichita Art Museum, Jewish Artists by Jon Catagno, American Paintings of Today, MOMA, as well as in exhibition catalogs of various museums and his one-man shows, more recently in a monograph for an exhibit in the 1990s, and the 2007 monograph Sidney Gross - A Vision Cut Short, Leonard Davenport and the ongoing biography project on the web at https://web.archive.org/web/20150925133242/http://www.lsdart.com/assets/Artist/grossbook.pdf.