The New Terrain of Global Governance: Mapping Membership in Informal International Organizations

We present a new dataset of membership in informal international organizations-IOs founded with non-binding instruments-which constitute one-third of operating IOs. We introduce state-IO-year-level membership data for 195 countries that complements the dataset on formal IOs from the Correlates of War Project. We explain our conceptualization of an informal IO, contrast it with other approaches, and detail the data collection process. We illustrate similarities and differences across formal and informal IOs, and across states and regions. We explain how our data validate or challenge conjectures about informal cooperation that have been inaccessible for lack of data. We demonstrate that while formal and informal IOs are similar in size, the composition of informal memberships in informal IOs is more fragmented. While informal IOs are a growing part of the governance portfolios of most states, some countries and regions participate more. We conclude by outlining elements of the research program our dataset unlocks.