The Library hosts a large number of books on international relations, international law and history. Upon request it provides many services such as specific studies, information processing or preparation of specific documentation dossiers. It also hosts the publications of the international organizations linked to the United Nations, as well as many others of the Council of Europe, the Organization for Economic Cooperation and Development, Nato, etc. The newspaper and periodical library has about 800 items, mostly coming from the International Organizations.

The international documentation Centre has a significant collection of documents of the United Nations and the League of Nations as early as their origins. It is both in English and French and it is filed according to the U.N. classification system. Since 1958 SIOI has also been a Centre of European Documentation.