Paris Bibliothque nationale de France MS Vma rs 571. The study of sacred music under Louis XIII r.1610-43 has advanced little in the past hundred years. Despite some important recent contributions by the late Denise Launay and others, much of our current perception of the Latin sacred music of the period is still informed by the pioneering research undertaken by Henri Quittard in the early years of the twentieth century. By re-examining one of the seventeenth-century treasures of the Bibliothque nationale MS Vma rs. 571, Sacred Repertories in Paris under Louis XIII reveals that, far from being a transitional period in which