Early life experiences are important precursors for developing leadership skills and acquiring formal leader roles later in life. The antecedents of leadership emergence in childhood have, however, not been subject to much empirical research—nor their links to actual leader role occupancy in adulthood. This study examines leadership emergence in a life-course perspective based on a large cohort of boys and girls, including survey and register data from the early 1960s to the late 2000s. We found a strong association between informal leadership emergence in childhood and formal leader role occupancy in adulthood. Social class was a significant predictor of both, mainly mediated through cognitive capacity and educational attainment in adulthood. Overall, the same factors predicted leadership emergence for both men and women. However, women received significantly more nominations for informal leader roles in childhood compared to men—accounting for a relatively larger share of the indirect effect of social class on holding a managerial position in adulthood. In contrast, the likelihood that a male held a managerial position in adulthood was relatively higher if he had been active in his spare time in childhood and had become a parent. Our findings thereby confirm the “parenthood advantage” for men vis-à-vis leadership role occupancy. With its prospective design and richness of data, the study shows how individual, structural, and behavioral factors interact in how leaders emerge across the life course, in general and among men and women respectively.