The Libellus de Diversis Ordinibus was written in the 1130s or 1140s, probably in the diocese of Liège, a recognized centre of religious and intellectual activity at the time. It is a description of the similarities and differences among the various orders of monks, canons, and hermits, and, though clearly a contribution to a contemporary debate, is more analytical than polemical. It is an invaluable source for religious life in the twelfth century. Unavailable for many years, the Oxford Medieval Texts edition has now been reissued with corrections.