When all citizens vote, the influence of radical parties decreases. Despite this being a central justification for compulsory voting in the past, it has been absent from contemporary debates. I examine the normative and empirical premises of the ‘moderation thesis’ in relation to radical right-wing populist parties today and suggest that, under certain conditions, compulsory voting can limit these parties’ appeal. First, it replaces the excessive mobilisation of discontented voters with a more universal mobilisation. Second, it addresses the problem of underrepresentation offering a more pluralist type of representation than the populist one. And third, it reverses socioeconomic inequalities that drive support for populism through the egalitarian effects that compulsory voting has on policymaking. My central thesis is this: because compulsory voting embodies inclusivist, pluralist and egalitarian values, it addresses some of the grievances that drive support for right-wing populist parties without carrying the same normative costs as populism.