This paper investigates the impact of national policies for improving teaching and the school learning environment (SLE) on student achievement. In each participating country (i.e., 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. National policies were measured through (a) content analysis of policy documents, (b) interviews with policymakers, and (c) head-teacher questionnaires. Multilevel analyses revealed that most aspects of national policies for teaching and SLE were associated with student achievement in each subject irrespective of the source of data used to measure them. Implications are, finally, drawn.