Joop Sanders is a Dutch-born, American painter, educator and founding member of the American Abstract Expressionist group. He is the youngest member of the first generation of the New York School.

Sanders was born in Amsterdam, the Netherlands and emigrated to the US in 1939. He became a US citizen in 1955. He is married to the lieder singer Isca Sanders. His son is the steel sculptor John Sanders and his daughter is the lawyer and environmental activist Karin Greenfield-Sanders. His son-in-law is the photographer Timothy Greenfield-Sanders and his grandchildren include artist Isca Greenfield-Sanders and filmmaker Liliana Greenfield-Sanders.

In 1940 Sanders met Willem de Kooning at a concert featuring the music of Virgil Thomson, Aaron Copland and William Schuman. As de Kooning was, Sanders is Dutch. He had immigrated to the U.S. in 1939. At the concert Sanders started talking to the woman sitting next to him. When he told her his name was Joop, she remarked, "Oh, is that Dutch? You have to meet my fiance who is also Dutch." The woman was Elaine de Kooning.

He studied in 1940 at the Art Students League of New York, in New York City, for six months with George Grosz. He studied in 1948 with Willem de Kooning.

Sanders was a charter member of The Club, which was located at 39 East 8th Street. The twenty original members of The Club were Landes Lewitin, Phillip Pavia, Willem de Kooning, Milton Resnick, Conrad Marca-Relli, Franz Kline, James Rosati, Ibram Lassaw, Al Copley, Ad Reinhardt, George Cavillon, John Roelants, Sanders, Ludwig Sander, Emanuel Navaretta, Charles Egan, Jack Tworkov, Gus Falk, Ahron Ben-Shnuel and Peter Grippe.

He exhibited in the legendary "9th Street Art Exhibition",held at 60 East 9th Street from May 21-June 10, 1951 alongside; Jackson Pollock, Robert Motherwell, Willem de Kooning, Elaine de Kooning, Albert Kotin. Milton Resnick, Joan Mitchell and Lee Krasner, among others.