What explains the rising support for populist parties in Europe over the last three decades: changes in partisan positions, changes in voters’ worldviews, or the weight voters attach to specific issues? In order to adjudicate between these three alternatives (though not mutually exclusive) arguments from the quickly-expanding literature on populism, we draw on decomposition methods developed in labour economics—a field of research that rarely engages in conversation with the populism scholarship. Decomposition methods allow us to quantify the relative contribution to the rise of European populism of the three aforementioned arguments, identify the marginal supporters of populist parties, and—last but not least—distinguish between common characteristics driving support for populism and idiosyncratic factors that explain support only in specific countries. Synthesizing data from the World Values Survey (WVS) with data on multidimensional party positions from the Comparative Manifesto Project (CMP), we show that the rise of populism is driven not so much by changes in voters’ worldviews but rather by changes in party positions on cultural issues and the weight voters attach to these issues. That being said, certain countries in Eastern Europe deviate from this general trend. Our findings help advance research on populism by tackling old questions with new methods.