- (1984) Hermits and the New Monasticism: A Study of Religious Communities in Western Europe, 1000-1150, Macmillan, ISBN 0333325826
- (1995) Medieval Women: A Social History of Women in England 450-1500, Weidenfeld & Nicolson, ISBN 1842126210
Collaborations
With Samuel Fanous (joint editors):
- (2005) Christina of Markyate ; A Twelfth Century Holy Woman, London & New York: Routledge,
With Richard Gameson (joint editors):
- (2001) Belief and Culture in the Middle Ages: Studies Presented to Henry Mayr-Harting. New York: Oxford University Press.