International studies of educational achieve-ment have been conducted since the 1960s. There are an increasing number of these kinds of studies and growing numbers of participating countries. Participation in international achievement studies allows for the comparison of performance with other countries and provides access to technical expertise in measurement and analysis, which can be shared and transferred. Vijay Reddy discusses the positives and negatives of such achievement studies, including the 2011 Trends in International Mathematics and Science Study (TIMSS).