Existing studies suggested that populist politics have a polarizing effect on party systems. This article examines how populist politics affects political polarization across 47 countries from 1996 to 2019. Using data on citizens’ perceptions of party polarization from the Comparative Study of Electoral Systems (CSES) and populism scores from the V-Party data (Lindberg et al., 2022), I construct a populism index at the macro level for 156 country elections. Empirical analyses show that populism intensifies ideological polarization among parties through mechanisms of polarizing populism and anti-populism in electoral regimes. While I find that populist parties’ access to government does not intensify party polarization, my results show that radical (left-right) populist parties positively affect party polarization. This study links to research on party politics, populist politics, and governmental representation and ideological radicalism of populist parties in established and democratizing regimes.
