The First Crusade (1096 – 1099) was an extraordinary undertaking. Because the repercussions of that expedition have rippled on down the centuries, there has been an enormous literature on the subject. Yet, unlike so many other areas of medieval history, until now the First Crusade has failed to attract the attention of historians interested in social dynamics. This book is the first to examine the sociology of the sources in order to provide a detailed analysis of the various social classes which participated in the expedition and the tensions between them. In doing so, it offers a fresh approach to the many debates surrounding the subject of the First Crusade.