Mark Gregory Pegg is a professor in the Department of History at Washington University.
Pegg researches, writes, and teaches on the thirteen centuries from 200-1500 that constituted the medieval West. His research focuses upon religion, heresy, persecution, and the problem of what defined human identity for over a millennium in the West.
Pegg’s scholarship has resulted in four books. His first book, The Corruption of Angels: The Great Inquisition of 1245-1246 (2001) is a study of the largest inquisition into heresy during the Middle Ages. It is a work of historical anthropology evoking the world of the almost six thousand men, women, and children interrogated by two inquisitors. His second book, A Most Holy War: The Albigensian Crusade and the Battle for Christendom (2008), is about the first crusade in which Christians were promised salvation by killing other Christians (accused of heresy). His third book, Beatrice’s Last Smile: A New History of the Middle Ages (2023) is a sweeping narrative of the medieval West from 200-1500, framed around the ebb and flow of holiness and humanity in the living of individual lives in the past. (It was a Times Literary Supplement Book of the Year and, most meaningful to him, Tom Holland’s Book of the Year for The Rest is History podcast.) His fourth book, The Cathar Curse: Medieval Heresies and Modern Heretics (2025), is a history of how the most famous medieval heresy, Catharism, never existed, except as an invention of nineteenth-century scholars, and how this fabrication continues to affect (or rather undermine) the history of heresy, religion, and historical truth.
Pegg has been awarded an Australian Research Council Fellowship, the Andrew W. Mellon Foundation New Directions Fellowship for the study of Arabic and religious violence in Christianity, Islam, and Judaism; and a Collegium de Lyon Institute for Advanced Studies Research Fellowship. He has been a Member of the Institute for Advanced Study at Princeton University and a visiting professor at the Université Paul Valéry Montpellier III.
Pegg received his bachelor’s degree with honors from the University of Sydney and his master’s and doctorate from Princeton University. He is originally from a small beach town north of Sydney. He misses the ocean.
