The literature on gender differences in competitiveness primarily focuses on individual labor market outcomes. However, Becker’s marriage theory suggests that it may also influence partners’ outcomes. Using Dutch household data, this study finds that, indeed, both men’s and women’s competitiveness strongly correlates with their own future incomes, even when controlling for education. However, only women’s competitiveness is significantly associated with their male partner’s future income, a relationship that remains robust after accounting for personality traits, couple fixed effects, and Oster’s (2019) criterion. In contrast, men’s competitiveness does not affect their female partner’s income. Thus, our evidence suggests that only women's competitiveness may have mating and cross-productivity effects on their partner’s future income. Notably, there is no evidence that women’s competitiveness boosts men’s income through household specialization. Work hours increase only with one’s own competitiveness for single and partnered men and women. Men’s competitiveness, however, increases their female partner’s housework and childcare hours, while women’s competitiveness does not reduce men’s domestic contributions. Additionally, the effect of women’s competitiveness on their partner’s income is moderated by their financial satisfaction. Our evidence suggests that women’s competitiveness may contribute to the gender income gap within and across couples.