This WebSite provides access to the results of a programme of cross-testing experiments conducted over the period 1993 to 1997, involving tests for aggregates that were being developed as European Standard methods by CEN/TC 154. The work was carried out as part of the EC DG XII Measurement and Testing programme. The cross-testing experiments used the latest available versions of the test methods, involved three levels (usually three different aggregates), and about fifteen laboratories. Results of the experiments are available, including data obtained, estimates of repeatability and reproducibility, and tables and graphs illustrating the results. Dissemination of the results of the experiments is being undertaken by video film, seminars, and by translations of key parts of the reports. Follow-ups include proficiency testing and the preparation of reference materials.