 "Belle nuit" is in the 6/8 time signature characteristic of barcarolles, "allegretto moderato".Approximately a minute of musical introduction occurs before the melody appears, although a flute accompaniment figure which suggests the melody, "suspend[ing] time" and creating anticipation for the melody before it begins, is played throughout the piece.Although it is sung by a juvenile male character, Nicklausse, in a "breeches role", and a female character, Giulietta, the fact of its being fundamentally a piece for two women's voices, intertwining in the same octave, means that in productions where Nicklausse has been played by a male baritone instead of a female mezzo-soprano, his part has been reassigned to a chorus soprano.