Almost all Western societies are characterized by social and ethnic inequalities in educational attainment. There is growing awareness of policymakers about the problems arising from such disparities, accompanied by attempts to reduce these inequalities by adequate educational policies. One strategy is to affect the parental educational decision-making process by manipulating students’ and parents’ freedom of choice at different transitions during the educational career and thereby affecting the possibility of selective educational decisions. However, it is so far unclear whether such educational policies work and if so, whether they are beneficial for reducing social and ethnic inequalities likewise. By using unique data from a quasi-experimental design comparing German- and Turkish-origin students at the end of primary school in Germany, I show that institutional settings reducing parents’ leeway to decide about the school tracks after primary school irrespective of prior achievement diminish social inequalities at the transition to upper secondary education. However, the relative disadvantage for Turkish-origin students and therefore ethnic inequalities increase in a more-meritocratic setting with less parental freedom of choice, especially for immigrant children with poorly educated parents. The study demonstrates that neglecting group-specific educational decision-making processes may thwart meaningful educational policies.