In this book I have traced the fight of the Genoese, Pisans and Venetians for privileged commercial status in the Norman kingdom of Sicily and southern Italy; and I have traced the exercise of that status where evidence exists. I have tried to show that Sicily and southern Italy played a special and crucial rôle in the commercial expansion of the north Italian towns. Not merely was the Norman kingdom a convenient base midway between the north Italian ports and more distant destinations such as the crusader states or Andalusia; not merely were luxury items available in the markets of Sicily, Campania and Apulia; but, in addition, the need to purchase wheat and raw cotton from the Norman kingdom made that kingdom a desirable and, ultimately, a wealthy ally. Most of the detailed evidence concerns Genoa (though it also speaks eloquently for Lucca), but the activities of the Genoese can themselves only be understood in the wider context of Pisan, Venetian, Greek and, on occasion, German attitudes to the Norman kings of Sicily. No apology seems necessary for the Genoese bias of his book, given the bias of the evidence; nor does apology seem necessary for the omission of Amalfi from this book. There is simply very little to say about the activities of the south Italian merchant cities on the basis of surviving twelfth-century sources. Nor does this work pretend to provide an overall survey of the trade of Norman Sicily. Such material as the Cairo Geniza documents, or other North African sources, may one day provide enough evidence for a study of twelfth-century trade between Sicily and the Islamic lands.