The international large-scale student assessments (ILSA) are on the scene of educational research for more than 50 years. Their role in policy-making in education as drivers for social change becomes more and more important over the last two decades. This presentation will provide an overview of the use of ILSA data for national policy-making in education and reforms’ implementation. The presentation will also provide a review of the theoretical and methodological assessment strategies for evaluation of the outcomes of education and their operational, methodological and psychometric complexities arising from the complex sampling and assessment designs. The issues stemming from these complex sample and assessment designs and their implications for analysis and interpretation of the results will be discussed. Limitations to the use of analysis techniques related with the data will be presented as well.