Which is a better determinant of achieving senior positions in management: ability or personality? In this study, over 50,000 adults, in very different organizations, completed a multidimensional intelligence test (General Intelligence Assessment), and a subsample (n = 2,368) also completed a personality test (High Potential Traits Inventory). They specified their age (modal 31 years), sex (34% female), and management level (ML; junior 34%, middle 39%, senior executive 27%). People at the most senior ML scored highest on all IQ subtests, particularly word meaning and number speed, but not perceptual speed. Regressions indicated that age, as expected, was the best predictor of ML but that gender, as well as word meaning and number score, was also significantly related to ML. Following correlations, which showed four traits (particularly ambiguity tolerance and conscientiousness) were related to ML, we performed regressions (hierarchical and ordinal logistic) to investigate to what extent there was incremental validity of personality over intelligence, and intelligence over personality, in explaining ML, controlling first for sex and age. Results suggested that personality added 4% incremental variance over intelligence, but the latter added less than 1% over the former. Traits ambiguity acceptance, risk approach, and conscientiousness were all significant predictors of ML. Limitations of various aspects of this study and implications for interventions are considered. Are people at different levels of management significantly different from each other in terms of their ability and personality? Do these factors contribute to their appointment and promotion? This study showed that personality factors are more important than ability factors, particularly the traits conscientiousness, tolerance for ambiguity, and approach to risk (courage), in explaining the difference between junior- and senior-management levels. Given the stability of these factors over time, it suggests they play an important role in the sort of individuals who rise to senior-management levels.