This study investigates whether or not the factor structure of reading comprehension is invariant across large, nationally representative samples of 14-year-old students from four different countries. The data were collected as part of the Reading Literacy Study of 1990/91, conducted by the International Association for the Evaluation of Educational Achievement (IEA). The relevance and application of multigroup confirmatory factor analysis techniques (Joreskog and Sorbom, 1988) to the assessment of model generalisability across countries or cultures, particularly in relation to international databases, is demonstrated and discussed.