Gottlieb was one of America's first Social Realist painters, influenced by the Robert Henri-led movement in New York City where Gottlieb settled in 1918. He was also a pioneer in screen printing, which he learned while working for the WPA.
In 1935, he joined the Federal Art Project; he was one of the first members of the WPA/FAP's Silk Screen Unit. Gottlieb remained active as a painter and screen printer after the closure of the Federal Art Project, and served as the first director of the short-lived American Artists School in New York City. Gottlieb was a leader and active member of the Artists Union and the Artists Congress.
He lectured widely on art education and promoted the government support of artist and artistic projects.