Using data from Project Implicit collected between 2005 and 2020, comprising 1,489,721 observations in 111 countries, we find that implicit and explicit gender stereotypes about career and family are more pronounced in more economically developed countries. Besides, these gender stereotypes are strongly correlated at the country level with gender differences in values (such as family values), self-reported personality traits (such as agreeableness or dependence), and occupational preferences (such as health-related occupations), and may account for the fact that these gender imbalances are "paradoxically" stronger in more economically developed countries (the so-called "gender equality paradox").In line with social role theory, our findings suggest that there are in developed countries strong gender stereotypes about career and family, which may at least partly explain the persistence or even the "paradoxical worsening" of a number of gender differences in these countries, despite generally high levels of gender equality in other areas.