She taught at HB Studio, a well-known New York City acting school on a cobblestone, tree-shaded street in the West Village. She began there in 1947, and married its co-founder, Herbert Berghof, on January 25, 1957. Later in her life, Hagen undertook a return to the stage, earning accolades for leading roles in Mrs. Warren's Profession (1985), Collected Stories, and Mrs. Klein. After Berghof's death in 1990 she became the school's chairperson.