Drawing on the literatures on negotiation and conflict resolution as well as research on international diplomacy, the author proposes a framework for understanding complexity in real-world negotiations. Rejecting models of the process that are simplistic, sterile, or static, he argues that complexity is inherent in negotiation. In ten propositions, he lays out key dimensions of complexity and ways that skilled negotiators can manage it. The propositions focus attention on the ways negotiators create and claim value, shape perceptions and learn, work within structure and shape the structure, negotiate and mediate, link and de-link negotiations, create momentum and engineer impasses, and work outside and inside. The author also highlights the importance of organizational learning in negotiation, noting that most negotiators manage multiple negotiations in parallel, and most organizations have many negotiators doing similar things.