Conflict is partly a matter of how planning institutions are supposed to act according to regulations, but also planning institutions' own ideas about power, consensus and democracy. Agonism is a critical mode of thinking about conflict and conflictual consensus. This chapter explores how planning praxis can work with conflict as agonistic conflict; what challenges does this give planning; positioned, as it is, within and relying on political legitimacy, consensus processes, and political decisions? It outlines three threads on agonism within planning theory and gives an introduction to the philosophy of agonism. The chapter discusses the challenges to planning theory given by the political philosophy on agonism from Chantal Mouffe by introducing her key concepts hegemony and 'war of position'. It introduces dissensus as a challenge to Mouffe's agonism and to planning using Jacques Rancière and discusses possible ways to work productively with agonism as 'a permanent provocation' and often representing dissensus to institutionalism and planning politics.