Abstract. This paper presents an argumentation mechanism for reconciling conflicts between planning agents related to plan proposals, which are caused by inconsistencies between basic beliefs regarding the state of the world or the specification of the planning operators. We introduce simple and efficient argument moves that enable discussion about planning steps, and show how these can be integrated into an existing protocol for belief argumentation. The resulting protocol is provably sound with regard to the defeasible semantics of the resulting agreements. We show how argument generation can be treated, for the specific task of argumentation about plans, by replacing the burden of finding proofs in a knowledge base by guided search.