INTERSALT was based on a common protocol and had a staff trained in standardized procedures in each center, thus permitting estimation of the sodium-blood pressure relationship within as well as across centers. INTERSALT originated as a Project of the Council on Epidemiology and Prevention of the International Society and Federation of Cardiology and has since its inception been jointly coordinated by the London School of Hygiene and Tropical Medicine and the Northwestern University Medical School. The main data analyses were performed in London. Overwhelmingly, funding for the work of the London Coordinating Center, the Central Laboratory, as well as for the 52 centers, had been organized independently. For example, support came from the Wellcome Trust, the World Health Organization, the International Society of Hypertension, the Council on Epidemiology and Prevention of the International Society and Federation of Cardiology, the Dutch Heart Foundation, the British Heart Foundation, the Canadian Heart Foundation, the Japanese Heart Foundation, as well as the private sector.