He and his wife Phoebe Brand, were identified as Communists by Elia Kazan, a Communist Party member himself at one time, in testimony before the HUAC in 1952, along with six other members of the Group Theatre. Actor Sterling Hayden testified before HUAC that he had attended Communist Party meetings that were sometimes held at Carnovsky's house in Hollywood. When Carnovsky was called before the HUAC he refused to "name names", which ended his film career. In 1975, he assessed the experience: