The devotion to the Seven Sorrows of the Virgin in the early sixteenth century has produced a treasury of music that has long interested musicologists. An illuminated choirbook, Brussels, Bibliothèque royale de Belgique, MS 215-16 (hereafter B-Br 215-16), contains plainchant, motets, and polyphonic masses, all of which celebrate the Feast of the Seven Sorrows.1 B-Br 215-16 was copied in the workshop of Petrus Alamire, a scriptorium that produced numerous illuminated music manuscripts, many of them for the Burgundian-Habsburg court.2 The plainchant of B-Br 215-16 is in fact tied to a competition organized by the court under the direction of Philip the Fair.