Today, thirty manuscripts prepared in Cavalli's workshop survive: twenty-eight in the Contarini collection of the Biblioteca Marciana in Venice, and two in the Osterreichische Nationalbibliothek in Vienna. This chapter focuses on Cavalli's copyists and the types of sources they copied. The primary job of the copyists working in the studiolo was to prepare scores and parts for the opera productions that Cavalli directed or oversaw in Venice. Cavalli's assistants obviously copied more than just production materials, since most of the surviving scores show no signs of having been used in performance. Jane Glover was the first to attempt a comprehensive study of the copyists in Cavalli's opera manuscripts. Glover proposed that many of the scribes working on Cavalli's scores were his students. Maria's most famous score, that of Poppea, was copied in an entirely different manner than Orimonte, Calisto, or Egisto.