Even though studies of supply-side populism are numerous, its connection with demand-side dynamics, and particularly the populist characteristics or tendencies of the electorate, requires more scholarly attention. We seek to examine in more detail the conditions underlying the support for populist parties, and in particular the role of populist attitudes amongst citizens. We ask two core questions: (i) to what extent are populist party supporters characterised by populist attitudes, and (ii) to what extent do populist (and other) attitudes contribute to their party preference? For the analysis, we use fixed-effect models and rely on a cross-sectional research design that uses unique survey data from 2015 and includes nine European countries. Our results are threefold. First, in line with single-country studies, we conclude that populist attitudes are prominent amongst supporters of left- and right-wing populist parties in particular. Second, populist attitudes are important predictors of populist party support, in addition to left-wing socio-economic issue positions for left-wing populist parties, and authoritarian and anti-immigration issue positions for right-wing populist parties. Third, we find that populist attitudes moderate the effect of issue positions on the support for populist parties, particularly for individuals whose positions are further removed from the extreme ends of the economic or cultural policy scale. These findings suggest that strong populist attitudes may encourage some voters to support a populist party whose issue positions are incongruous with their own policy-related preferences