This chapter deals with musical life in Santiago cathedral during the 16th to 18th centuries. It considers, among other topics, its organization, structure, financing, and the agency of specific people, such as bishops, prebendaries, chapelmasters, and other musicians. It subsequently explains how this information casts light on more musical issues, such as performing practice, particularly during José de Campderrós’s time. The chapter also studies the repertoire, including plainsong and intonations, Latin polyphony, and Spanish pieces (especially villancicos), showing that the relative scarcity of music sources can be related not only to the restricted budget of the institution (especially until 1700) but also to specific features proper to is musical life. Then, it relates the different kinds of music mentioned before to the liturgical context, explaining both some of its similarities and differences with other cathedrals from the New World. As in the rest of the book, this chapter combines the study of historical documents and music sources.