The literature on party organization and populism has uncovered significant insights into the leadership structures within populist parties. This article extends that understanding by examining by applying the conceptual framework of personalization to political parties \citet{pedersen2023personalisation, rahat2023personalizationa}. This framework makes a clear conceptual distinction between personalism, the situation in which a party is dominated by the will of a single leader, and within party personalization, the process whereby a party becomes increasingly leader-centric. The main hypotheses are that both are linked to an increase in a party's level of populism. Using a subset of the V-Dem Party \citep{Lindberg2022} dataset encompassing 398 parties across 30 parliamentary democracies (1975–2019), the findings demonstrate that parties identified as more leader-centric exhibit significantly higher levels of anti-elitism and people-centrism compared to less centralized counterparts, and that temporal increases in leader centralization within parties correspond to significant rises in populism. These results have implications for the understanding of the broader phenomena of personalization and populism in advanced democracies.
