John of Ibelin, count of Jaffa and Ascalon (d. 1266), was one of the foremost politicians in the kingdom of Jerusalem in the mid-thirteenth century; his family was prominent in the Latin East, and linked by ties of marriage to the royal dynasties of both Jerusalem and Cyprus. John's career and his ancestors' rise to prominence are the subject of the first half of this book. The second concentrates on John's most lasting achievement, his treatise on the pleading, procedures and customs of the High Court of the kingdom of Jerusalem, which includes descriptions of the ecclesiastical hierarchy, the juridical structure and the military capacity of the kingdom; this material provides invaluable insights into the kingdom's institutions, government and resources; it is here re-edited from the best surviving manuscripts and discussed in detail. Dr PETER W. EDBURYis Reader in Medieval History at the University of Wales, Cardiff.