Abstract. Argumentation-based techniques are being increasingly used to construct frameworks for flexible negotiation among computational agents. Despite the advancements made to date, the relationship between argument-based negotiation and bargaining frameworks has been rather informal. This paper presents a preliminary investigation into understanding this relationship. To this end, we present a set of negotiation concepts through which we analyse both bargaining and argumentation-based methods. We demonstrate that if agents have false beliefs, then they may make decisions during negotiation that lead them to suboptimal deals. We then describe different ways in which argument-based communication can cause changes in an agent’s beliefs and, consequently, its preferences over contracts. This enables us to demonstrate how the argumentation-based approach can improve both the likelihood and quality of deals.