In musicology, the fifteenth century has traditionally been considered a decisive period in the development of musical institutions. This chapter focuses on the establishment of musical chapels in European courts. It provides an overview of types of musical functions in courtly, ecclesiastical, and civic contexts. These functions provided the institutional grounding for all musical practices, serving to project exclusivity and cachet to the outside world and foster internal stability and identity. The chapter describes the development of representative court chapels in the fifteenth century. The institutional positioning of figural music in court chapels went hand in hand with the changing dynamics of political processes. New developments created a pan-European field of engagement, intensifying contacts and conflicts among political actors across the Continent. Several innovations attended the growth and professionalization of the musical apparatus of courtly liturgy: musical settings of the Ordinary in England, Burgundy, and France and their modification and expansion in the Milanese motetti missales.