The Eton Choirbook (Eton College MS. 178) is a richly illuminated manuscript collection of English sacred music composed during the late 15th century. It was one of very few collections of Latin liturgical music to survive the English Reformation, and hence is an important source. It originally contained music by 24 different composers; however, many of the pieces are damaged or incomplete. It is one of three large choirbooks surviving from early-Tudor England (the others are the Lambeth Choirbook and the Caius Choirbook).
The Choirbook was compiled between approximately 1500 and 1505 for use at Eton College; its present binding dates from the mid 16th century. 126 folios remain of the original 224, including the index. In the original, there were a total of 93 separate compositions; however only 64 remain either complete or in part. Some of the 24 composers are known only because of their inclusion in the Eton Choirbook. John Browne has the most compositions (10), followed by Richard Davy (9) and Walter Lambe (8).
Stylistically, the music contained in the Eton Choirbook shows three phases in the development of early Renaissance polyphony in England. The first phase is represented by the music of Richard Hygons, William Horwood and Gilbert Banester. Most of the music of this early phase is polyphonic but non-imitative, with contrast achieved by alternation of full five-voice texture with sections sung by fewer voices. The second phase, which includes music by John Browne, Richard Davy and Walter Lambe, uses imitation, cantus firmus techniques, and frequent cross-relations (a feature which was to become a distinctive sound in early Tudor polyphony). The final phase represented in the choirbook includes music by William Cornysh and Robert Fayrfax, composed around 1500. Points of imitation are frequent, cantus firmus techniques disappear, and in general the sound of the music is more Continental.