Spanish church music prior to the work of Francisco de Penalosa at the end of the fifteenth century has been much neglected, partly because much of it is anonymous and scattered throughout a number of manuscripts. This book aims to redress the balance, identifying and examining nearly 70 pieces of surviving Latin sacred music written in Spain between 1400 and the early 1500s, and discussing them source by source; the author argues that they reveal a rapid and dramatic change, not only in style and sophistication, but in the level of self-consciousness they demonstrate, creating a new national music as Ferdinand and Isabella of Spain were creating a new nation. He moves on from this to set Penalosa's work, written in a more mature, northern-oriented style which influenced Iberian composers for generations after his death.