Despite considerable changes in the gender gap regarding educational qualifications and labor force participation, the share of female managers has changed only slowly and continues to be low. This paper adds new evidence to the study of the dearth of women in top managerial positions in firms by documenting and analyzing data on beliefs about own managerial abilities collected from survey of a large sample of Danish managers. We develop measures for gender stereotype attitudes and beliefs about ability, distinguishing between masculine and feminine skills, and examine whether these are correlated with each other and differ by gender. We find that especially female C-level managers differ substantially from managers at levels below. Female medium and lower-level managers’ beliefs in own ability is lower than for their male peers for two reasons: weaker prescriptive gender stereotype attitudes and lower miscalculation of abilities, possibly less overconfidence. The weaker ability beliefs contribute to reduced self-confidence and career ambitions and to the explanations for the lack of women in top positions.