Farrar was born in Melrose, Massachusetts, the daughter of baseball player Sidney Farrar, and his wife Henrietta Barnes. At age five, she began studying music in Boston and by 14 was giving recitals. Later she studied voice with the American soprano Emma Thursby in New York City, in Paris, and finally with the Italian baritone Francesco Graziani in Berlin. Farrar created a sensation at the Berlin Hofoper with her debut as Marguerite in Charles Gounod's "Faust" in 1901 and remained with the company for three years, during which time she continued her studies with famed German soprano Lilli Lehmann. (She had been recommended to Lehmann by another famous soprano of the previous generation, Lillian Nordica.) She appeared in the title roles of Ambroise Thomas' "Mignon" and Jules Massenet's "Manon", as well as Juliette in Gounod's "Roméo et Juliette". Her admirers in Berlin included Crown Prince Wilhelm of Germany, with whom she is believed to have had a relationship beginning in 1903.