The authors use data from the Children of the National Longitudinal Survey of Youth (C-NLSY79) to examine gender differences in the associations between child behavioral problems and early adult earnings. They find large and significant earnings penalties for women who exhibited more headstrong behavior and for men who exhibited more dependent behavior as children. By contrast, the authors observe no penalties for men who were headstrong or for women who were dependent. Although other child behavioral problems are also associated with labor market earnings, their associations did not differ significantly by gender. The gender differences in headstrong and dependent behavior are not explained by education, marriage, depression, self-esteem, health, or adult personality traits. One potential explanation is that these gender differences are a consequence of deviations from gender norms and stereotypes in the workplace.