 Her performance as Ulrica in Giuseppe Verdi's "Un ballo in maschera" at the Met was the only time she sang an opera role on stage.Anderson worked for several years as a delegate to the United Nations Human Rights Committee and as a "goodwill ambassadress" for the United States Department of State, giving concerts all over the world.She participated in the civil rights movement in the 1960s, singing at the March on Washington for Jobs and Freedom in 1963.