This essay presents some of the preliminary results of an extensive study begun in 1996 under the auspices of the Théâtre Baroque de France1 and continued in collaboration with the musicologist Jerôme de la Gorce until the Théâtre closed in 1998.2 The study was devoted to the troupe of the Académie Royale de Musique, otherwise known as the Opéra, and aimed at producing an annotated catalogue of the casts from all the works staged by the Opéra between 1699 and 1733.3 To accomplish this, we established the calendar of performances and then began collecting all the corresponding libretto-programs.4