Nadia Boulanger ([ʒy.ljɛt na.dja bu.lɑ̃.ʒe]; 16 September 1887 – 22 October 1979) was a French composer, conductor and teacher who taught many composers and performers of the 20th century.

From a musical family, she achieved early honours as a student at the Paris Conservatoire, but believing that her talent as a composer was inferior to that of her younger sister Lili, she gave up composing and became a teacher. In that capacity she influenced generations of young composers, including many from the U.S., beginning with Aaron Copland. Among her other students were those who became leading soloists and conductors, including Dinu Lipatti, Igor Markevitch and Ástor Piazzolla. She also taught Philip Glass.

Boulanger taught in the U.S. and in England, working with music academies including the Juilliard School, the Yehudi Menuhin School, the Royal College of Music and the Royal Academy of Music, but her principal base for most of her life was her family's flat in Paris, where she taught for most of the seven decades from the start of her career until her death at the age of 92.

As a conductor Boulanger was the first woman to direct many major orchestras in America and Europe, including the BBC Symphony, Boston Symphony, Hallé, New York Philharmonic and Philadelphia orchestras. She conducted several world premieres including works by Copland and Stravinsky.