Negotiation research began in the 20th century and is continuing apace. It is pursued from the perspectives of several disciplines including psychology, organizational behavior, labor relations, decision sciences, game theory, communications, legal studies, international relations, public policy, and others. Added to these are best practices from several fields engaged in intervention in conflicts. By now we have accumulated a considerable volume of wisdom regarding what drives people and entities to negotiate, how they behave when doing so, how they should handle negotiations to obtain specific results, and how to help disputants resolve to come to joint, mutually satisfactory decisions. However, negotiation wisdom remains rather distributed in its disciplines and practices of origin. Arguably, negotiation as a field of practice has yet to come together under a shared theoretical umbrella, with a shared vocabulary, and broadly agreed-upon propositions and prescriptions valid across the board. In this Article, we ask whether such a unified “grand” theory can be constructed, and if so, how.