Ellis was born in Manhattan, New York City, to German parents, Herman Elsas and Caroline Elsas ("née" Reinhardt), who was a pianist. She first became interested in performing around 1910, and under a vocational course trained her lyric soprano under the tutelage of Belgian contralto Freida de Goebele and Italian operatic coach Fernando.Tanara. She made her debut with the Metropolitan Opera on December 14, 1918, in the world premiere of Puccini's "Il trittico", creating the role of Genovieffa in "Suor Angelica", the second of the evening's three one-act operas. Later in the run, she also played Lauretta in the third opera of the triptych, "Gianni Schicchi." She also appeared in the premiere of "L'oiseau bleu" by Albert Wolff, singing Mytyl, in 1919. While in the Metropolitan company she sang Giannetta in "L'elisir d'amore" to Enrico Caruso's Nemorino and Fyodor in "Boris Godunov" to Feodor Chaliapin's Boris.