This dissertation re-establishes Paris, through its symbiotic relationship with the royal court, as a major centre for the production, performance and transmission of sacred and secular polyphonic repertoires at the turn ofthe fifteenth century. It shows that the French royal court anchored in Paris represented an important point of reference for all musicians, including the composers Jean Vaillant, Jacquet de Noyon, J. Solage, Jean Carmen and Jean Cesaris, and paves the way for new interpretations ofthe surviving musical repertoires. Chapter 1 underlines the importance ofParis to the careers of musicians active in royal courtly circles as an ideal location for the development of networks ofsocial and professional acquaintances for musicians. The clerical nature of singers' and organists' training set them on a par with those clerks employed in the royal court and the governmental bodies based on the lIe-de-la-Cite, who patronized polyphonic music in the capital's ecclesiastical institutions. Chapter 2 focuses on the Sainte-Chapelle ofParis as a centre of musical excellence. The Sainte-Chapelle was linked to the court, through accumulation ofoffices and frequent movements ofpersonnel, and to the citY, through accumulation ofbenefices at Parisian churches and chapels. Sainte-Chapelle musicians performed during processions through Paris, at royal courtly events contexts or on more private occasions patronized by clerks active in royal service. Chapter 3 highlights points ofcontact between musicians active in the University quarters and those active at the royal court, setting the scene for the transmission and discussion of courtly repertoires in the University. Information concerning the patronage of polyphony at the Dormans College by clerks active in royal service supports the theory of shared musical repertoires at court and in the University.