A network of virologic laboratories has been established by the World Health Organization to conduct surveillance for wild poliovirus and to provide evidence for the certification of poliomyelitis eradication. The network consists of >60 national laboratories isolating and identifying polioviruses within countries; 16 regional reference laboratories, providing intratypic differentiation of wild and vaccine strains and assisting with quality assurance and training; and 6 global specialized laboratories, conducting research, preparing reference reagents, and providing genomic sequencing of wild polioviruses, advanced training, and expert virologic advice. Laboratories collaborate with national eradication programs in the detection, reporting, clinical investigation, and virologic testing of stool specimens obtained in connection with cases of acute flaccid paralysis and, where indicated, from healthy children and the environment. A quality assurance system, leading to World Health Organization accreditation, involves training in standardized techniques, use of centrally prepared typing antisera, annual proficiency testing and follow-up action, and monitoring of standard performance indicators.