Among her students were many important composers, soloists, arrangers, and conductors, including Grażyna Bacewicz, Daniel Barenboim, Lennox Berkeley, İdil Biret, Elliott Carter, Aaron Copland, David Diamond, John Eliot Gardiner, Philip Glass, Roy Harris, Quincy Jones, Gilbert Levine, Dinu Lipatti, Igor Markevitch, Julia Perry, Astor Piazzolla,[2] Laurence Rosenthal,[3] and over 250 others.

When Ernest brought Nadia home from their friends' house, before she was allowed to see her mother or Lili, he made her promise solemnly to be responsible for the new baby's welfare.

[14] In 1903, Nadia won the Conservatoire's first prize in harmony; she continued to study for years, although she had begun to earn money through organ and piano performances.

At her accompagnement exam, Boulanger met Raoul Pugno,[15] a renowned French pianist, organist and composer, who subsequently took an interest in her career.

[17] In addition to the private lessons she held there, Boulanger started holding a Wednesday afternoon group class in analysis and sightsinging.

This class was followed by her famous "at homes", salons at which students could mingle with professional musicians and Boulanger's other friends from the arts, such as Igor Stravinsky, Paul Valéry, Fauré, and others.

"[16] Her goal was to win the First Grand Prix de Rome as her father had done, and she worked tirelessly towards it in addition to her increasing teaching and performing commitments.

[16] The subject was taken up by the national and international newspapers, and was resolved only when the French Minister of Public Information decreed that Boulanger's work be judged on its musical merit alone.

[16][21] In 1908, as well as performing piano duets in public concerts, Boulanger and Pugno collaborated on composing a song cycle, Les Heures claires, which was well-received enough to encourage them to continue working together.

[22] Still hoping for a Grand Prix de Rome, Boulanger entered the 1909 competition but failed to win a place in the final round.

Nadia struggled with the death of her sister and according to Jeanice Brooks, "[t]he dichotomy between private grief and public strength was strongly characteristic of Boulanger's frame of mind in the immediate aftermath of World War I.

Boulanger was invited by Cortot to join the school, where she taught classes in harmony, counterpoint, musical analysis, organ and composition.

[36] Her close friend Isidor Philipp headed the piano departments of both the Paris Conservatory and the new Fontainebleau School and was an important draw for American students.

She inaugurated the custom, which would continue for the rest of her life, of inviting the best students to her summer residence at Gargenville one weekend for lunch and dinner.

[37] Boulanger's unrelenting schedule of teaching, performing, composing, and writing letters started to take its toll on her health; she had frequent migraines and toothaches.

[44] Boulanger's private classes continued; Elliott Carter recalled that students who did not dare to cross Paris through the riots showed only that they did not "take music seriously enough".

[45] By the end of the year, she was conducting the Orchestre Philharmonique de Paris in the Théâtre des Champs-Élysées with a programme of Bach, Monteverdi and Schütz.

[47] Later in the year, she traveled to London to broadcast her lecture-recitals for the BBC, as well as to conduct works including Schütz, Fauré and Lennox Berkeley.

[16][48] Boulanger's long-held passion for Monteverdi culminated in her recording six discs of madrigals for His Master's Voice in 1937, which brought his music to a new, wider audience.

[50] When Hindemith published his The Craft of Musical Composition, Boulanger asked him for permission to translate the text into French, and to add her own comments.

In November, she became the first woman to conduct a complete concert of the Royal Philharmonic Society in London, which included Fauré's Requiem and Monteverdi's Amor (Lamento della ninfa).

[52] Describing her concerts, Mangeot wrote, She never uses a dynamic level louder than mezzo-forte and she takes pleasure in veiled, murmuring sonorities, from which she nevertheless obtains great power of expression.

She is quite slim with an excellent figure and fine features, Her skin is delicate, her hair graying slightly, she wears pince-nez and gesticulates as she becomes excited talking about music.

[58] Waiting to leave France till the last moment before the invasion and occupation, Boulanger arrived in New York via Madrid and Lisbon on 6 November 1940.

[59] After her arrival, Boulanger traveled to the Longy School of Music in Cambridge, Massachusetts, to give classes in harmony, fugue, counterpoint and advanced composition.

Her attitude to women in music was contradictory: despite Lili's success and her own eminence as a teacher, she held throughout her life that a woman's duty was to be a wife and mother.

The less able students, who did not intend to follow a career in music, were treated more leniently,[79] and Michel Legrand claimed that the ones she disliked were graduated with a first prize in one year: "The good pupils never got a reward so they stayed.

"[82] Boulanger used a variety of teaching methods, including traditional harmony, score reading at the piano, species counterpoint, analysis, and sight-singing (using fixed-Do solfège).

She would quote the examples of Rameau (who wrote his first opera at fifty), Wojtowicz (who became a concert pianist at thirty-one), and Roussel (who had no professional access to music till he was twenty-five), as counter-arguments to the idea that great artists always develop out of gifted children.

[93] Janet Craxton recalled listening to Boulanger's playing Bach chorales on the piano as "the single greatest musical experience of my life".