This work offers an up-to-date discussion of medieval Castilian lordship and social relations, approached through an analysis of behetria lordship, a power-structure of fundamental importance in medieval Castile. The origins of behetria lordship, a complex phenomenon in both theory and practice, are obscure. Knowledge of the behetrias has therefore hitherto been limited to a narrow circle of traditionalist, highly specialized legal historians. The present volume redresses this imbalance, as its various contributors explore the question of behetria lordship from a broad social perspective, thereby demonstrating the crucial role played by this seigneurial structure within medieval Castilian society. This collection of essays thus focuses less on legal intricacies than on deeper social, territorial, and political issues, which are also examined in relation to other better-known forms of lordship exercised both within Castile and beyond. This volume provides rich historical material on medieval Castile rarely available to an English readership; it represents a gateway to a wealth of relatively little-known literature and information on the social history of medieval Spain, and will provide an invaluable tool for comparative research.