The Yearbook of International Organizations provides the most extensive coverage of non-profit international organizations currently available. Detailed profiles of international non-governmental and intergovernmental organizations (IGO), collected and documented by the Union of International Associations, can be found here. In addition to the history, aims and acitvities of international organizations, with their events, publications and contact details, the volumes of the Yearbook include networks between associations, biographies of key people involved and extensive statistical data.

Providing both an international organizations and research bibliography, Volume 4 cites over 46,000 publications and information resources supplied by international organizations, and provides nearly 18,000 research citations under 40 subject headings. This volume also includes a research bibliography on international organizations and transnational associations.