This article demonstrates how meta-analytic techniques, that have typically been used to synthesize findings across numerous studies, can also be applied to examine the reasons why relationships between background characteristics and outcomes may vary across different locations in a single multi-site survey. This application is particularly relevant to the analysis of data from international surveys of student achievement. A brief introduction to the method of meta-regression is provided and the technique is demonstrated in an analysis of the extent to which the relationship between school autonomy and achievement varies depending upon the level of accountability in a country. The results show that the meta-regression approach to analysis is more accurate than combining data across all countries into a single simple model.