Negotiation is essential in settings where agents have conflicting interests and a desire to cooperate. In many approaches, agents are assumed to have pre-set, fixed preferences, and complete awareness of the space of possible outcomes. Such strong conditions are often not satisfied. In this paper, we argue that since preferences are adopted to pursue particular goals, one agent may influence another agent’s preferences by discussing the underlying motivations and interests behind adopting the associated goals. We identify concepts that seem essential for supporting this type of dialogue. In particular we demonstrate that arguing about beliefs needs to be complemented by arguing about goals, and we begin an analysis of dialogue moves involving goals. Categories and Subject Descriptors I.2.11 [Artificial Intelligence]: Distributed Artificial Intelligence—intelligent agents, multiagent systems, languages and structures General Terms Design, Economics, Languages, Theory Keyword...