Research on the supply side of politics demonstrates that populism acts as a common denominator even though populist parties possess very different ideological positions. However, it is uncertain whether this translates to the demand side: Do voters support left and right-wing populist parties for similar reasons? Using the Netherlands as our case study, we investigate the common demand side characteristics of supporters of populist radical right and populist radical left parties. The paper concludes that populist attitudes (i.e. a people-centered notion of political representation) unify supporters of both populist radical left and populist radical right parties. Supporters of both parties also demonstrate lower levels of political trust (than voters for other parties): this is particularly the case for PVV supporters. Beyond these similarities we find that the PVV and the SP attract very different supporters. PVV supporters demonstrate low immigrant tolerance, while SP voters support more income equality.