In the last 5 years, we worked intensively, within the context of the SONAR-project, at the implementations of a detailed longitudinal database on the transition from school to work among Flemish youth. With this research project we wish to further examine why women, compared to men, enter less easy into, and take in less interesting positions at, the labour market. This despite the better educational achievement of girls in school. In a meritocracy, it normally is expected that better school results also induce better labour market opportunities. But women still are concentrated in less paid jobs. To explain the gender differences in the transition from school to work, we advance two crucial elements: the different subject choice of boys and girls on the one hand, and the rol of family formation and parenting on the other hand. With this research project we will study the extent to which subject choice and family formation reverse the advantage of girls at school to a disadvantage at the entrance into the labour market en for the further development of the professional career. The SONAR-data will be used as main source for the analyses, but we also plan to check and compare our results with other databases (the data of LOSO, other databases available in the research group, and data of internationally comparable research.