She made her debut at the Lyric Chicago Opera in 1959, and at the Metropolitan Opera in 1961, as Leonora in "Il trovatore". She was to sing at the Met for twenty-four consecutive seasons. Amongst her greatest roles are the female lead in operas such as Verdi's "Ernani", "Un ballo in maschera", "La forza del destino", Mozart's "Don Giovanni" and "Cosi fan tutte", Puccini's "Manon Lescaut", "Madame Butterfly", "La fanciulla del West", Richard Strauss's "Ariadne auf Naxos", etc.