This book examines the career of Emperor Frederick II vis-à-vis the Latin East, arguably the East-West relationship that did most to shape the fate of the kingdom of Jerusalem in the thirteenth century. It is a novel approach, both to the emperor himself and to the wider subject matter, as previous studies have not focused specifically on this aspect of Frederick's life, or so closely pursued this particular aspect of relations between the Latin East and the West. Guy Perry offers a detailed analysis of the period 1215-50 (that is, between Frederick first taking the cross at his German coronation, and his death thirty-five years later). However, the book also provides a summary of Frederick's paternal and maternal legacies - the Hohenstaufen and Hauteville 'family traditions' of crusading, established in the twelfth century. The study looks forward too, taking the opportunity to examine, in as much detail as possible, the neglected reigns of Frederick's son, Conrad IV, and of the emperor's grandson, Conradin, as kings of Jerusalem (effectively covering 1250-68). The book therefore encompasses the vast majority of the thirteenth century, offering a panorama of East-West relations during this period.