The international survey programmes implemented under the auspices of the International Association for the Evaluation of Educational Achievement (IEA) have a long- established and well-respected presence in the assessment world. Together with the OECD's more recently launched Programme for International Student Assessment (PISA) we now benefit from a wealth of information about the nature and relative effectiveness of educational systems around the world. And yet some countries continue to maintain their own systems of national assessment, running alongside the international programmes. Why do some governments choose to support both forms of enterprise, given the significant financial and other costs involved? What need do they see for national assessment programmes in this global context? What can national assessment tell us that PISA (and TIMSS and PIRLS) cannot? The presentation focuses on this question, using as illustration examples from a number of different European countries.