The UK National Audit Office (NAO) commissioned RAND Europe to look at the evidence showing the effectiveness of reform of mathematics teaching in primary schools in England. This study looked at government-sponsored evaluations of mathematics reform in England, independent evaluations of the educational outcomes of mathematics reforms in England, and the international evidence regarding some of the main components of government policy aimed at improving educational outcomes. The study presents the results of the evaluations and the international literature and discusses the robustness of their findings.