Countries around the world are striving to improve their educational systems with a view to improving their economy and society. In this global competition, national and international test results are of considerable interest. In this paper, we show that national testing in England and the USA have shown little or no improvement over the years. This finding is not isolated; it appears to be a global phenomenon. Data from large-scale international assessments such as PISA, TIMSS and PIRLS are remarkably stable over time. This paper reviews the trends from country-specific and international data and explores some of the reasons which have been offered for such stability. We argue that these explanations are insufficient and ways forward are discussed.