The purpose of this paper is to raise a problem of more than antiquarian interest in Reformation literary history. The Unio Dissidentium is a collection of passages from the Bible together with nearly 550 quotations, many of them quite lengthy, from the Fathers. This latter feature gives to the book much of its interest, as well as a place in the patristic revival begun by the classical humanists and brought to a high level of development by the work of such men as Erasmus and Beatus Rhenanus.So far as can with certainty be stated, the first part of Unio Dissidentium was published by the Antwerp printer, Martin de Keyser, in March 1527. The ten sections into which it is divided contain passages supporting the compiler’s theology on such current theological issues as original sin, infant baptism, predestination, the nature and function of law, grace and merit, faith and works, and human ordinances. Later that same year the same printer published the second part, dealing with the value of the Word of God, penitence, brotherly correction, fasting, prayer, indulgences, the Eucharist, ecclesiastical constitutions, the vocation of all Christians to be priests, kings, and prophets, and antichrist. To the editions printed in and after 1531 a further three sections were added, the first two of which are on expensive funerals and the flight and persecution of Christians, respectively, while the third is the tract of Pseudo-Augustine, De Essentia Divinitatis.