This book is a sophisticated comparative analysis of the doctrine of unjust enrichment in the North American and Jewish legal systems, and in international law. Dagan offers an explanatory theory which reveals the normative underpinnings of the doctrine, facilitates the prediction of legal outcomes, and supplies the necessary tools for evaluating existing legal rules. The theory of unjust enrichment is seen to be implicated in the prevailing background ethos of the societies he studies, and deeply influenced by their conceptions of self and community.