The administration of the Norman Kingdom of Sicily has long been held up to be the most advanced government in twelfth-century Europe. However, until now there has been considerable confusion about how this bureaucracy actually functioned, whether it developed in the 12th century or retained the form given it by Roger II; whether it had regional variations, what the identity of different departments of government was, who did what within the structures of government, and what the relationship between the Greek, Arabic and Latin elements within the administration was.This work goes a long way to sorting out these problems. The author's meticulous work with chronicles and charters enable him to clear up many problems and mysteries in the administration of finance and justice and to identify such uncertainties as remain. This fundamental work forms a basic reference point for future studies of Norman Sicily and of government in the high Middle Ages.