Despite their generally higher educational attainment, young women are characterised by lower labour market positions than men in Belgium. Using regression and decomposition analyses on data from the longitudinal SONAR survey on the transition from school to work, we examine to what extent subject choice and processes of family formation can explain the gender differences on labour market positions at the age of 26 (N = 2060). We find that both subject choice and family formation influence labour market outcomes and that these factors can partially explain the gender gap. Both factors, however, differ in their interaction with gender. While subject choice has a similar effect for both men and women, family formation has a negative impact on the labour market position of women only. (Contains 3 tables and 9 notes.)