The history of monasticism in early Ireland is dominated by its flourishing during the sixth and seventh centuries, a period dominated by Columba of Iona and Columbanus of Bobbio, and later by the ‘reform’ spearheaded by Malachy of Armagh during the twelfth century. But what of monasticism in Ireland during the intervening period? Regarded as different from ‘mainstream’ Anglo-Saxon and continental monasticism, monastic life in Ireland has not been fully understood in scholarly discussions about the existence of distinct ‘monasticisms’ throughout Christianity. The Irish sources, many written in the vernacular, are not readily accessible and are viewed as unconventional. The secularization of monasticism in Ireland has overshadowed evidence for a thriving lived monasticism. This major study concentrates on those men and women who followed a monastic life, especially between the tenth and thirteenth centuries, and who maintained a universal monastic ideology while incorporating monasticism into their own cultural environment.