Exchange transactions constitute the core of our economic system and, not surprisingly, contract law occupies a central place in the legal curriculum. Contract law’s predominance has never been more evident, as new 21st century technologies expand the nature and province of consensual exchanges and emerging political systems explore the limits of contract-based economies. In this environment, legal decision makers must consider, among other things, the need for new rules and principles to govern novel forms of transactions, such as electronic standard-form contracting and software licensing, and to police against overreaching that results from unique kinds of market failures. Further, recent work exploring the nature of assent and applying cognitive psychology, critical theory, techniques of legal planning, and other tools, increases our understanding of the nature and function of contract law and demonstrates the breadth of contract law’s domain.