Internationally comparative research in education which is aimed at investigating the relationships and processes that explain possible differences between educational systems has so far relied on the replication of the same analysis using different data sets. Patterns of results from these analyses have allowed for the examination of differences, uniquenesses or similarities of the way in which factors operated in various countries. However, it has not been possible to test the extent to which effects varied across countries. Recent technological and methodological advances have made it possible to move beyond replication to the systematic and rigorous testing of structural and causal models of educational processes and outcomes across countries. For the examination of structural models, simultaneous analysis allows for the testing of the invariance of parameter estimates in one anlaysis while maintaining the separation of the different data sets. In conjunct analysis, data from different countries are combined in a way that takes into consideration the different levels of data collection while maintaining links between the levels. Data collected by the International Association for the Evaluation of Educational Achievement (IEA) provide a massive amount of information that awaits appropriate analyses to address important research question in the field of comparative education. In this monograph, data collected in the Reading Comprehension Study and the Reading Literacy Study are employed to illustrate the application of simultaneous and conjunct analyses. This monograph endeavours to illustrate how recent methodological advances in internationally comparative research might contribute to gaining a better understanding of educational processes and outcomes in cross-national analyses.