Theory and evidence indicate that, if family size grows, the younger children will get less parental involvement than the older children. These differences in parental involvement through birth order may impact academic achievement if, and only if, parental involvement is an important determinant of children’s educational attainment. The oldest child then benefits the most in terms of educational outcomes. Estimates for the Netherlands show a robust negative relationship between birth order and parental involvement, and significant positive medium to large effects of parental involvement through birth order on various measures of academic achievement. Furthermore, our findings indicate that academic achievement is rooted in a school-supportive home climate, and often created by the mother. However, when it comes to math performance and grade retention, it is better that both parents unduly interfere with school. We also find that parents with low socio-economic status and from immigrant families are as much involved in the education of their children as the average Dutch family, but their involvement is less effective in terms of children’s learning outcomes.