A part-book preserved in the Instituto Espanol de Musicologia, Barcelona, contains over fifty items of sacred music by composers associated with both the Cathedral and the Colegio de los Infantes in Toledo during the sixteenth and early seventeenth centuries. These composers range from Morales and Guerrero, to Francisco de Tapia and Jorge de Santa Maria-both Masters at the Colegio in the later sixteenth century- and Alonso Lobo, chapelmaster at the cathedral, 1593 to 1603. The majority of the music is unique to this source, and it also includes works by Morales that were revised for publication when he was in Italy. The part-book is very largely copied for second or first superius, and there are indications that much of the repertory was intended for high voices; but there is also the occasional piece for a lower voice part. The manuscript contains a wide range of Latin-texted sacred music that includes mass settings, Magnificats, motets and psalms. In addition to about a dozen items by Morales, the partbook includes rare settings of calendas by Santa Maria, examples of mass propers in contrapunto style by Francisco de Tapia, and a sequence of music for the Christmas Misa del gallo (midnight mass).