The paper researches the peer effects in the primary education system of the Netherlands. This will be accomplished by evaluating data from a cohort study in Dutch primary education 2007-2013. This data provides among other things; the social economic status, test scores and advices regarding secondary education given by teachers. The main finding regarding peer effects show that peer effects mainly work in a negative way. The findings of advices given by teachers reveals that teachers tend to give relatively higher advices to students in poor classrooms.