Boulay’s Trois Pièces place her firmly within the musical style of fin-de-siècle Paris through the use of rich chromatic harmonies, expressive melodies, and careful attention to line and voice-leading, demonstrating a use of chromaticism and dissonance that stay within the bounds of functional harmony. Unlike some of her contemporaries who wrote music that could be played on the organ or the harmonium (making it more marketable), the Trois Pièces are unequivocally for the organ. They each feature an independent pedal part, and the Prélude and Andante call for three manuals, specifying registrations that utilize multiple solo stops. The Prélude unfurls a lyrical melody over an A B B’ A’ form, creating repetition on a large scale while also repeating musical motives and rhythmic patterns within sections. A study in various modulatory techniques, the piece begins and ends in c# minor, but modulates to or briefly tonicizes many other key areas as remote as B major and C major.