* The Religious Orders in England (3 volumes)
* The Benedictines in England
* The English Religious Tradition
* The Life and Times of St. Gregory the Great
* From Pachomius to Ignatius: A Study in the Constitutional History of the Religious Orders
* The Monastic Order in England: A History of its Development from the Times of St. Dunstan to the Fourth Lateran Council
* Christian Monasticism
* The Evolution of Medieval Thought
* The Historian and Character
* Great Historical Enterprises: A Comparative Study
Articles:
* "The Place of Monasticism in the Church"
* "The Religious Orders in the Middle Ages"
* "The Benedictine Ideal"
* "The Cistercians"
* "The Franciscans"
* "The Dominicans"
* "The Carmelites"
* "The Augustinians"
* "The Premonstratensians"
* "The Gilbertines"
Other Writings:
* Editor, The Oxford Dictionary of the Christian Church
* Contributor, The Cambridge Ancient History
* Contributor, The Cambridge Medieval History
* Contributor, The New Cambridge Modern History