Abstract: The private and the social functions of contracts and of contract law are examined in this entry. In section 1, on the basic theory of contracts, the topics considered include contract formation, why contract enforcement is valuable, the incompleteness of contracts, the interpretation of contracts, remedies for breach, renegotiation of contracts, and judicial overriding of contracts. In section 2, the economic literature on production contracts is reviewed, and in section 3 other types of contract are discussed.