Thus wrote William of Malmesbury, around 1124, of the impact on monastic life of the coming of the Normans to England. In Yorkshire, the subject of this book, the ‘rule of monastic life’ had indeed perished, and nowhere was the rapid expansion of monasticism in England in the course of the late eleventh and twelfth centuries more dramatic. In this study I explore the growth of the monastic order in this one county – the largest in England – between c. 1069 and c. 1215, and set detailed analysis of its history in the wider context of contemporary British and European movements. The time span calls for some explanation. The year 1069 marks the reintroduction of formal monasticism to the north in the wake of the damage wrought by the Viking invasions and internal decline, after which the weakness of royal authority had prevented the monastic reforms of the tenth century in the south and midlands from reaching north of the Trent. I use the words ‘formal monasticism’ advisedly. It is tempting to write off the north as a monastic desert, but this ignores both the continuity, in some form, of the Community of St Cuthbert, first at Chester-le-Street and then at Durham; and the possibility of the existence of a monastic sub-culture, which has left little trace on the written records.