The Yearbook of International Organizations is a comprehensive resource of intergovernmental (IGOs) and international nongovernmental organizations (INGOs) worldwide.

"The Yearbook of International Organizations is the definitive directory of more than 75,000 governmental and non-governmental nonprofit organizations worldwide, including both active and dormant entities. For decades, it has been published by Brill on behalf of the Union of International Associations (UIA)—a non-governmental research institute and documentation center based in Brussels; further information is available at https://uia.org/yearbook/. There are no comparable works of its scope, and its closest rival—the similarly formatted Encyclopedia of Associations: International Organizations published in a three-volume print (56th ed., 2017) and an ebook edition on the Gale Virtual Reference Library (CH, Dec'10, 48-1793) platform—pales in comparison. The UIA/Brill resource is truly an omnibus endeavor sui generis. Navigation of the online licensed edition is straightforward, with links on the home page corresponding to the set's six printed volumes. Paralleling the contents of the first three volumes, one can search by name, location, and subject. The latter is ostensibly facilitated by employing the database's own rubrics extracted from profile titles and descriptions, but unfortunately, searching in this manner results in some irrelevant returns, and one may be better off using keywords as search terms. The granularity of the otherwise robust search interface also enables more refined searches by fields such as membership, the year the organization was founded, where it is headquartered, and the venues of past and future meetings. An elaborate coding system categorizes organizations by type (national organizations, those with universal membership, etc.). Replicating the remaining volumes in the set, there are also links to an extensive bibliography on international organizations, statistics about them, and the Who's Who in International Organizations (CH, Mar'04, 41-3767) volume. Open Yearbook at http://uia.org/ybio/ is UIA's free service, and it offers all of the entries in the full-feature database but with only basic searching capability of the limited information about an organization's history and aims; the particulars about activities, structure, staff, financing, publications, membership, and scheduled events updated every six to eight weeks in the fee-based online version are restricted to paying subscribers. The gargantuan print edition, in six hefty tomes published annually, totals thousands of pages. But as stated in the prefatory notes, it sometimes omits full descriptions, unlike the online edition. The fact that the organizations themselves are the principal sources speaks to the credibility of the information in the profiles, which include "many bodies that may be perceived as not being fully international, or as not being organizations as such, or as not being of sufficient significance to merit inclusion." With print-reference purchases declining and academic library shelf space at a premium, the annual subscription to the digital version is the obvious choice for those institutions that can afford it. Practically speaking, however, the free version should suffice for most users if supplemented by internet searches, albeit labor intensive, to find information on the organizations' own websites." - D. Ettinger, George Washington University

The Union of International Associations (UIA) is a research institute and documentation centre, based in Brussels. It was founded over one hundred years ago, by Henri La Fontaine (Nobel Peace Prize laureate of 1913), and Paul Otlet, a founding father of what is now called information science. Non-profit, apolitical, independent, and non-governmental in nature, the UIA has been a pioneer in the research, monitoring and provision of information on international organizations, international associations and their global challenges since 1907. For more information, visit: http://www.uia.org