- The Americas in the Spanish World Order: The Justification for Conquest in the Seventeenth Century
- Popes, lawyers, and infidels: The church and the non-Christian world, 1250-1550 (The Middle Ages)
- Empire and Order: The Concept of Empire, 800-1800 (Studies in Modern History)
- Competing Voices from the Crusades: Fighting Words
- John Adams and the Constitutional History of the Medieval British Empire