While working on a play Hay met actor Will Geer, with whom he entered into a relationship. Geer was a committed leftist, with Hay later describing him as his political mentor. Geer introduced Hay to Los Angeles' leftist community, and together they took part in activism, joining demonstrations for laborers' rights and the unemployed, and on one occasion handcuffed themselves to lamposts outside UCLA to hand out leaflets for the American League Against War and Fascism. Other groups whose activities he joined in with included End Poverty in California, Hollywood Anti-Nazi League, the Mobilization for Democracy, and Workers' Alliance of America. Hay and Geer spent a weekend in San Francisco during the city's 1934 General Strike, where they witnessed police open fire on protesters, killing two; this event further committed Hay to societal change. Hay joined an agitprop theatre group that entertained at strikes and demonstrations; their performance of "Waiting for Lefty" in 1935 led to attacks from the fascist Friends of New Germany group.