The need for engaging citizens in climate policymaking is increasingly recognised. Despite indications that the form of expert involvement can strongly shape the outcomes, this remains scarcely researched. We analysed two unique and contrasting cases of citizen engagement in national climate mitigation policy: 1) the Irish Citizens' Assembly (ICA), the rst national climate assembly involving live expert presentations and face-to-face deliberations; and 2) the Participatory Value Evaluation (PVE) on Dutch climate policymaking, where more than 10,000 citizens compared policy options in an online environment based on expert-based information on policy effects. Taking a dramaturgical approach, we found that the opening-up and closing-down of policy options and perspectives was in uenced by the setting, staging and scripting of expertise. The simple and online format of the PVE allows for opening-up towards a diverse set of normative perspectives, but a small set of policy options. In contrast, the deliberative setting of a climate assembly enables deliberation on a wider set of policy options, but a limited range of normative perspectives. Apart from providing information on policy options, experts had signi cant roles in design choices and formulating recommendations, which further shaped citizens' deliberations and policy advice. Future research should further investigate the role of experts and expertise across a wider range of practices. Nevertheless, we conclude that the high degree of required technical knowledge in climate mitigation policy naturally implies a strong in uence of expert involvement, which concomitantly steers the results. Alternatively, we may search to enhance citizens' engagement in guiding climate policymakers focusing on citizens' normative perspectives.