This volume presents English translations, with introductions and notes, of Latin sources for the Fourth Crusade (1202-1204). The sources consist of forty-one letters from the registers of Pope Innocent III; the three extant versions of the letter of 1203 that Count Hugh of Saint Pol dispatched to the West; The Devastation of Constantinople (DC); the account of the Anonymous of Soissons; passages from the Deeds of the Bishops of Halberstadt; and, the chronicle accounts of Ralph of Coggeshall and Alberic of the Trois Fontaines. Now with critical editions of the DC and the Anonymous of Soissons in appendices. By virtue of the different perspectives through which they viewed the crusade, these sources combine to deepen our understanding of this complex and controversial moment in Western-Byzantine relations.