Italian opera is increasingly receiving well deserved attention. Yet the process by which the chorus in opera seria was created remains largely unexplored. Between 1759 and 1769 Tommaso Traetta and Christoph Gluck composed path-breaking, reform-inspired opere serie for Parma’s Teatro Ducale which integrated chorus, dance and stage spectacle in the French manner. In an era when operatic choruses usually comprised amateurs and chapel singers, evidence from printed librettos and documents from Parma’s Archivio di Stato reveal that many of the Teatro Ducale’s choristers were professional singers hired from neighbouring Bologna. Perhaps in response to logistical and financial difficulties in engaging skilled personnel for Traetta’s choruses, Parma established a singing school to provide choristers for theatre. Gluck’s choruses employed a combination of students from this school and professionals. The evidence from Parma shows that the wide-ranging circuit within which Italy’s opera theatres functioned embraced not only leading soloists and other personnel, but choral singers as well. It demonstrates the impact of practical circumstances surrounding the production of Parma’s operatic choruses on the success of operatic reform in Parma.