Intergovernmental organization data, 1816-1964

Data for 237 intergovernmental organizations (IGOs) extant between 1815 and 1967 are included in this study. The membership status of 148 countries is recorded for each organization at five-year intervals. A nation is coded as being a full member of the particular IGO during the given time period, as associate member, a member of the international system but not a member of the IGO, or as not a member of the system.