As some of the most experienced political actors, party leaders usually have extensive careers spanning multiple decades, competencies, and institutions. The literature on party leaders, however, has not yet incorporated the wealth of information that these careers have. Therefore, this article introduces career capital as a new continuous measure of political experience and hypothesizes that more career capital leads to longer tenure. In contrast to findings from previous studies, I show that career capital does contribute to party leaders’ survival in office in several analyses of party leader duration in Canada, Germany, the Netherlands and Switzerland in the postwar period (1945–2023). In addition, because career capital is accumulated in three separate institutions, I examine the differences between these descriptively and show in the analysis that especially previous experience in legislative office is conducive for party leaders to remain longer in office. Lastly, the results indicate that the relationship between career capital and party leader duration is non-linear and subject to the effect of attrition, signifying that political experience acquired shortly before entering party leader office is more important for political survival.