Born in Walla Walla, Washington, Marion Bauer grew up in Portland, Oregon before moving to New York to live with her sister, Emilie Francis Bauer, who worked as an editor and critic for the Musical Leader for 25 years. In 1906, at the invitation of the French pianist Raoul Pugno, Marion went to France where she met Nadia and Lili Boulanger. Nadia suggested that they exchange lessons; Marion taught Nadia English, and Nadia gave Marion lessons in harmony. This arrangement continued until Bauer returned to the United States in 1907; it supports her claim that she was the first American student of Nadia Boulanger. In 1912, Schmidt Music signed Bauer to a seven year contract and that year published seven of her songs which received favorable reviews. Throughout her career Bauer continued to compose and publish orchestral works, chamber music, vocal and instrumental pieces. She was highly regarded as a teacher, serving on the faculties at New York University and the Juilliard School of Music. After the death of her sister in 1926, Bauer assumed the post of New York editor of the Musical Leader until her own death in 1955. Although she maintained a mostly impressionistic style in her compositions, she was a champion of new music. She lectured frequently on the subject and urged teachers to use modern pieces to accustom their students to dissonances and other "unusual" sounds. She served on the executive board of the League of Composers and wrote several articles and books, including the well-known Twentieth Century Music.