The paper investigates how (de)legitimization and impoliteness are interconnected in the ethno-sectarian conflicts that take place in online news response threads. (De)legitimization is conceptualized as a micro argumentative practice that can index the interlocutors’ sociopolitical stances and position them in relation to each other in inter-group contestations. Using multi-tiered positioning analysis, a distinction was made between exogenous and endogenous impoliteness assessments each of which occurred at a different spatiotemporal level of the interactions. This distinction elucidates how impoliteness assessments can trigger and be triggered by (de)legitimization. To understand how (de)legitimization might trigger impoliteness assessments, this paper differentiates between face-related and identity-related impoliteness, which were both used strategically to deepen the ethno-sectarian divisions in this online context. In the online conflicts in question, collective impoliteness was sometimes motivated by legitimization, rather than delegitimization, even though legitimization involves no violation of the genre-sanctioned interactional norms or the moral order. That was because legitimization functioned in binary oppositions, and, as such, was perceived by out-group members as provocative impingement on their ethno-sectarian communities’ sociopolitical rights.