The standards set by the National Measurement Accreditation Service (NAMAS) and its laboratories are followed world-wide. The use of NAMAS experience to develop other countries' accreditation systems is extensive and shows no sign of abating. The article gives a background to NAMAS, its role in the National Measurement System (NMS) and its approach to the accreditation of calibration and testing laboratories. It also describes the roles played by the Western European Calibration Cooperation (WECC), by the Western European Laboratory Accreditation Cooperation (WELAC) and by the European Organisation for Testing and Certification (EOTC).