While the parametric models suggest there is a formal premium, and it remains after controlling for individual and firm characteristics, the semi-parametric tests used in this article indicate either a negative or a small and insignificant formal premium. Advances in women’s educational attainments and increased opportunities for women in the labour market have narrowed the wage gap between men and women and improved women’s representation in high-status occupations (Ridgeway and Corell, 2004). Some researchers have argued that the wage gap between men and single women is not significant; nevertheless, the differences in earnings between men and married women remain high (Gangl and Ziefle, 2009). Given the traditional role of women as caregivers, in addition to the traditional wage gap, mothers seem to be the ones who experience most disadvantages, and this “motherhood penalty” has been identified in wage differentials between mothers and non-mothers that control for other human capital factors typically explaining wage differentials.