At the latest since the PISA study, the international comparability of educational system performance is called for. Little discussion takes place on the research problems occurring in the course of internationally comparative educational systems in the social societal teaching subjects. Research, however, finds itself confronted with methodical, scientific-theoretic and test-ethical problems. These problem areas are to be outlined in this paper. The focus will be on quantitatively comparative education studies. Essentially the analysis consists of an examination of the ICCS Study (International Civic and Citizenship Education Study) of the biggest internationally comparative political education study in existence.