This article examines the specific difficulties involved in conducted statistical comparisons of educational levels in Europe. The first difficulty concerns the educational and political history of each country. A second relates to comparison indicators, and a third is dependent on the identification of the populations on which the comparison is conducted. Finally, the paper examines the challenges presented by international harmonization and compares the ISCED-97 nomenclature with its earlier version as well as with other classifications used by sociologists in their comparisons of large numbers of countries, including as the Casmin nomenclature.