This European project investigates the impact of the school factors included in the dynamic model of educational effectiveness on student achievement. In each participating country (Belgium/Flanders, Cyprus, Germany, Greece, Ireland and Slovenia), a sample of at least 50 schools was drawn and tests in mathematics and science were administered to all grade 4 students (n = 10,742) at the beginning and end of school year 2010-2011. Teachers completed a questionnaire measuring school policy on teaching, the school-learning environment and the evaluation of school policy. Multilevel analysis revealed that the school factors measuring policy on teaching, the school-learning environment and the evaluation of school policy explain student achievement gains in mathematics and science across countries and in each participating country. The effect sizes of these factors are equally important for explaining variation in student achievement in each subject. Descriptive analyses also show that there is scope for improving the factors included in the dynamic model in each country. Implications for research, policy and practice are drawn.