What conditions must be met for citizens to decide to engage in political participation and bring their interests and preferences into the political process? Political science studies have identified three central explanatory factors: resources such as money, time, and education; attitudes towards political involvement; and social networks. However, the precise interaction of these factors, particularly the possibility of interactive relationships, has not yet been examined. For instance, it is conceivable that increasing political interest leads to stronger participation only among those citizens who have good resource endowments, while less well-off citizens remain excluded from the political process even with strong interest—a concerning finding from a normative perspective. Emanuel Hansen investigates political participation behavior in five European countries (Germany, France, Poland, Sweden, and Spain). Cross-nationally, significant and substantively meaningful interaction effects emerge between the key determinants of political participation. The normative implications of unequal political involvement must be regarded as even more problematic in light of this new finding than previously assumed in political science discussions.