Her family was musical; her sister, Kristine, is a soprano. Both girls grew up to be internationally-known opera headliners. (Their publicity says there are only three other instances in the history of opera when pairs of sisters have both reached comparable heights.)
They pursued and developed their careers differently: Katherine trained in the United States and her career has centered in that country more than has her sister's.
Katherine graduated from Newark High School in 1968 and attended Temple University in Philadelphia. After receiving a bachelor of music degree there (summa cum laude), she remained in the same city to study voice at the Curtis Institute of Music. She earned her master's, with honors, and a certificate in opera performance in 1973.
She also studied at the Marlboro Music Festival (1975-1977) and the Sommerakademie of the Mozarteum in Salzburg, Austria. In 1976 she won First Prize at the Geneva International Music Competition and was a winner at the Concert Artists Guild Competition. In 1977 at the Concours International Chant de Paris, she was acclaimed First Prize winner by unanimous decision of the jury.
Her Carnegie Hall recital debut was in 1977. She has frequently appeared in recital and concert, and on leading opera stages in the United States and Europe, including regular appearances at the Metropolitan Opera, the Houston Grand Opera, and at the Stuttgart Opera, Canadian Opera, Royal Opera House Covent Garden (London), Scottish Opera, San Francisco Opera, and Dallas Opera. Some of her roles are Cassandra in Berlioz' Les Troyens, Laura in Ponchielli's La Gioconda, Judith in Bartók's Bluebeard's Castle, and Adalgisa in Bellini's Norma. She has appeared in world premieres of Dominick Argento's The Aspern Papers, Maurice Ohana's Le Celestine, Girolamo Arrigo's Il Ritorno di Casanova, Par Vir's Snatched by the Gods, Mark Adamo's Little Women, and Jake Heggie's The End of the Affair.