Evaluation and accountability are key issues in ensuring quality provision for all.. In Europe, the dominant arrangement for educational accountability is school inspections. Annually an average amount of 68.559.103 euros is spent on inspecting schools in every country in this project. Inspectorates of Education assess the quality of education and hold schools accountable for a broad range of goals related to student achievement, teaching, organization and leadership in schools. Growing evidence indicates that school inspections can be a key feature of school improvement. More recent studies however also point to unintended consequences such as excessive bureaucracy and teaching to the test. Good measures and methods of school inspections are therefore crucial in promoting quality within schools. In this proposal we aim to study how different types of school inspections in Europe promote high educational and student achievement in schools, answering the following research question:What aspects of school inspections (standards and threshold, sanctions and rewards and, frequency of visits) contribute to effects (improvement of educational quality and student achievement) and unintended consequences (strategic behavior) in schools?Different types of European school Inspectorates are included in our quasi-experimental comparative study, ranging from school Inspectorates using a low stakes professional development inspection approach, to test-based early warning inspections to control schools. The results of this project will include evidence of measures, instruments and working methods of school Inspectorates contributing to improvement of schools and student achievement. The instruments developed in this project will be available to other Inspectorates to improve the impact of their work. Close cooperation with the European organization of School Inspectorates (SICI) will promote the use of results and instruments to improve education across Europe.