One of the most striking characteristics of the music from the Spanish kingdoms at the time of Ferdinand and Isabel in comparison with other musical traditions of the same period is the relative scarcity of sources of instrumental and polyphonic music. This lack can partly be explained by the loss of many manuscript sources and the late introduction of music printing in Spain; El Maestro by Luis Milán, printed in 1536, is the earliest Spanish collection of solo instrumental music and accompanied songs, as well as the first printed Spanish tablature. However, there is a third reason: the importance of oral tradition in the transmission and performance of music in Spanish culture during the Renaissance, in both sacred and secular contexts. This essay will survey the different traditions of unwritten music in Spain at the time of the Catholic Monarchs: in the liturgical context, particular emphasis will be placed on the transmission and performing practices of extempore counterpoint and unwritten fabordones; and in the secular context, several aspects related to the oral repertory of vernacular songs, both polyphonic and accompanied, as well as instrumental music will be considered.