The Eton Choirbook, compiled for liturgical use at Eton College around 1500, provides a unique view of English music at the turn of the sixteenth century; no other comparable repertoire source for this time has survived the depredations of the English Reformation. Among the 25 choice composers represented stands the name of William Cornysh, contributing eight pieces to this national anthology of devotional music. He also composed 13 of the secular part songs in a 1520 anthology of music known as Henry VIII's Songbook, after its collector and principal contributor. Clearly Cornysh held the respect of King and Church alike; very little straightforward information about his life, however, survives. In fact, recent scholarship suggests that these two repertoires may be the work of two separate individuals: William Cornysh the elder, composer of the mature Eton Choirbook church music, and William Cornysh the younger (possibly his son), actor, singer, and courtier. A small number of early documents list payments to a William Cornysh for compositions, and for participation in courtly dramas and "disguysings," the earliest dating from 1494. He spent time in prison starting in 1502, producing a pamphlet of versified defenses while incarcerated. Apparently his term was brief, as his 1501 appointment as a Gentleman of the Chapel Royal was never revoked, and he was appointed Master of the Children for the Chapel establishment in 1509, a position he held until his death in 1523. Records of court dramatic presentations in 1511 and 1514 credit him with musical collaboration, and his presence leading the royal singers across the Channel in 1513 and again at 1520 during the celebrations on the field of the Cloth of Gold is well-documented. As late as June 1522, the court received a play of his, celebrating the diplomatic visit by the Holy Roman Emperor. The surviving sacred music of "Cornysh" in the Eton Choirbook shares with much of that repertory a thick, melismatic texture, a noble breadth of vocal range, and a penchant for biting cross-relations and other dissonances. His splendid and popular setting of the Marian text "Salve regina" from this source exemplifies the style. Indeed, his contributions to this volume bespeak a surprising maturity of hand. In his time, however, William Cornysh Jr. (presuming that both repertoires are his) seems to have been far better known for his secular work, as a song composer, actor, playwright, and stage director, and one at the center of the Tudor court's secular culture. A song of his from Henry VIII's Songbook, A robyn, gentle robyn, may have been the song Shakespeare intended the clown to sing in the fourth act of Twelfth Night.