Pernicious polarization is an antagonistic Us versus Them division, where the other group is perceived as an existential threat. It is often intertwined with the erosion of democratic norms and institutions. Although studies on polarization abound, there are still some blind spots to be filled. Our contribution is the focus on the mesolevel of civil society and the theoretical development of (de)polarization mechanisms at this level. Empirically, we study think tanks, a special type of civil society organization, in the context of democratic backsliding in Hungary and Poland. The analysis is based on 53 interviews with Hungarian and Polish think tankers conducted between 2020 and 2022. We contend that through a shift in perceptions of Us, Them, and the middle ground, think tanks contribute to both polarization and depolarization. Rather than being passive receptors of polarization dynamics, we showcase think tanks’ agentic roles as they emerge through these three mechanisms and through think tanks resorting to specific patterns of discourse and interactions.