Thomas Netter of Walden (c. 1374 - 1430) was a Carmelite friar, royal confessor, diplomat, religious superior, and theologian. His only extant theological work, the Doctrinale antiquitatum fidei catholicae ecclesiae contra Wiclevistas et Hussitas, was written with the declared purpose of combating the errors of Wyclif and his followers. For this reason, Netter's name and work are familiar mainly to those engaged in the study of Lollardy. Outside this field, Netter is almost unknown today, yet in his lifetime he was a highly regarded churchman who, it was said, could have had the pick of any diocese in England. From his death in 1430 until the middle of the eighteenth century, Netter was a much-quoted and copied author whose exposition of Catholic teaching on subjects such as the Church, religious life, and the sacraments proved useful to many Counter-Reformation polemicists and apologists. This book is the first survey of the whole of the Doctrinale and it argues that there is more to Netter than anti-Lollard polemic. The author examines the principal topics in Netter's work - God, humanity, Christ, the Church, religious life, prayer, the sacraments - and he makes the case that there is a definite plan which links the various parts of the Doctrinale into a whole giving it a certain theological unity.