Schools are increasingly expected to take responsibility for aspects of educational quality assurance. The fact that the Flemish government requires its schools to conduct self-evaluations of their equal opportunities policies is an example of this. This article reports on the findings of a study that investigated the quality of these school self-evaluations and the impact of key factors of policy effectiveness on quality aspects of these self-evaluations. The headteachers of a representative sample of schools (N = 580) that pursue equal opportunities for all pupils were questioned by means of a written survey. The results indicate that most headteachers take the view that their school performed well on the quality aspects of the school self-evaluation. However, there are considerable differences between schools. School scores with regard to the quality indicators of school self-evaluations show a correlation with aspects of schools’ policy-making capacities. On this basis, the concepts of policymaking capacities and policy effectiveness seem to be a promising tool with regard to the description, monitoring and improvement of the quality of school self-evaluations.