The frail, dark-eyed young woman was vying for the greatest accolade in music—the hotly contested Prix de Rome for the year 1913. The field had been narrowed to five composers whose cantatas were to be evaluated by a vote of 36 members of the Academie des Beaux-Arts. One critic attending the final judging of the cantatas contrasted contestant Lili Boulanger with the rest of the competitors:

Perched over the piano like jockeys over the necks and withers of their horses, the intrepid composers spurred on their accompanists and desperately flailed away at the performers. Then the superiority of the eternal feminine became apparent to the audience. Compared to her hot-blooded colleagues—who apparently believed that “their hour had come”—the young girl, who had just as much reason to be nervous and impatient, showed the most perfect poise. She had a modest and unaffected attitude, her eyes lowered to the score.

Another witness reported that the three singers with the composer's sister Nadia at the piano, were directed by Lili Boulanger, standing nearby, “a slender shadow in a white dress, so simple, calm, serious and smiling as to be unforgettable.”

But as far as the judging was concerned, the outcome was by no means a sure thing. On the previous day, the preliminary vote by a panel of eight had given Lili Boulanger's cantata a scant majority of five votes. Now it was up to the 36 to decide. After considering the merits of the candidates and other prizes they had won, the members voted. Of the 36, 31 voted in favor of Lili Boulanger and her cantata on the basis of intelligence of subject, correctness of performance, sensitivity and warmth, poetic feeling, and intelligent, colorful orchestration.

With her personality, her poise, and her cantata, Lili Boulanger had set a precedent. In the 110-year history of the Prix de Rome, she was the first woman to win.