[2] From 1928 to 1932, she was a member of the alto section of the Mendelssohn Club, a historic choir which at that time performed often with the Philadelphia Orchestra under conductor Leopold Stokowski.
That same year she sang the Voice of the Mother of Antonia in The Tales of Hoffmann and the shepherd boy in Tosca with the Philadelphia Orchestra under conductor Alexander Smallens.
[4] In 1935, Harshaw won the National Federation of Music Clubs singing competition which gave her a $1,000 cash prize and led to her New York City concert debut on July 21 of that year at Lewisohn Stadium under conductor José Iturbi.
[6] In 1936 she entered the graduate program at the Juilliard School where she studied voice with Anna Eugénie Schoen-René who had been taught by the legendary Pauline Viardot, daughter of the Spanish singer and pedagogue Manuel García.
Her Wagner roles during these years included Brangäne in Tristan und Isolde, Erda, Flosshilde, and Fricka in Das Rheingold, Erda in Siegfried, the First Norn and Waltraute in Götterdämmerung, Fricka and Schwertleite in Die Walküre, Magdalene in Die Meistersinger von Nürnberg, Mary in The Flying Dutchman, Ortrud in Lohengrin, Venus in Tannhäuser, and Kundry and the Voice from Above in Parsifal.
Other roles in her Met repertoire included Amelfa in Le Coq d'Or, Auntie in Peter Grimes, Azucena, Amneris in Aida, Frugola in Il Tabarro, Geneviève in Pelléas et Mélisande, Gertrud in Hänsel und Gretel, Herodias in Salome, La Cieca in La Gioconda, Mistress Quickly in Falstaff, the Mother in Louise, the Third Lady in The Magic Flute, and Ulrica in Un Ballo in Maschera.
By 1954 she had completely left the mezzo repertoire, with the exception of Ortrud, and effectively succeeded Helen Traubel in the Wagnerian heroine roles of Brünnhilde, Elisabeth, Isolde, Kundry, and Sieglinde.
Her final and 375th performance at the Met was as Ortrud on March 10, 1964 with Jess Thomas as Lohengrin, Leonie Rysanek as Elsa, and Joseph Rosenstock conducting.
She was committed to the San Francisco Opera between 1944 and 1947, portraying such parts as Amneris, Azucena, Brangäne, Fricka, Geneviève, Herodias, La Cieca, Mistress Quickly, Ortrud, Ulrica, and the Nurse in Boris Godunov.
Among her many students were Laura Aikin, Gary Burgess, William Burden, Katherine Ciesinski, Vinson Cole, Pablo Elvira, Franz Grundheber, Constance Fee, Kevin Langan, James Allen “Jimmy” Smith, Jr., Shirley Love, Mark Lundberg, Nancy Maultsby, Emily Magee, Ronald Naldi, Reginald Pittman, Matthew Polenzani, John Reardon, Nadine Secunde, Martha Sheil, Gregory Stapp, Sharon Sweet, Michael Sylvester, Rebecca Turner, Benita Valente, Christine Weidinger, and Kathryn Bouleyn Day.