ABSTRACT Democratic innovations scholars note that deliberation has the potential to counteract populism. However, so far, we do not know what the theoretical foundation would be to expect such an effect, nor do we know to what extent the supposed effect actually materialises empirically. This study adds to the literature by offering a theoretical framework and by testing this framework empirically. Specifically, we examine to what extent citizens with a high degree of populist attitudes became less populist after participating in a deliberative event. We study an actual citizens' assembly on climate mitigation policy in the Netherlands via pre- and post-surveys and carry out an SEM analysis (N = 105). We find that citizens with a higher degree of populist attitudes do become less populist, but find no evidence that this is due to the (perceived quality of the) deliberation. At the same time, the climate skeptics who participated became more populist.