The International Union of Anthropological and Ethnological Sciences (IUAES) is the largest world forum of anthropologists and ethnologists, with members from more than fifty countries.

The earliest predecessor of the IUAES was the International Congress of Anthropology and Prehistoric Archaeology, which was founded in La Spezia, Italy, in 1865.

Meetings were scheduled for every four years, but only one more congress was held, in Copenhagen, Denmark, in 1938, before World War II made it impossible for people to convene.

It was formed under the aegis of UNESCO and became a member of the International Council for Philosophy and Humanistic Studies (ICPHS), which it remains to this day.

To ensure the financial autonomy of the Union from its congresses, in 1998 it was decided to again separate the presidency of the IUAES from that of each succeeding ICAES.

The executive committee is the main regulatory body, making policy decisions on behalf of, and subject to the authority of, the Permanent Council.

The structural guidelines of the IUAES are given in its Statutes, which have grown from a simple set of rules into an array of constitutional by-laws.

The IUAES Commissions, of which more than thirty are currently recognized,[1] determine their own administrative structure and set of activities, which generally include the organization of panels, workshops, and sessions at the quinquennial ICAES.

These needs were formally acknowledged under the leadership of Cyril S. Belshaw, president in the period 1978–1983, who sensed that "the mood is to place the Union on an active footing".

[3] The IUAES Congresses and Inter-Congresses catalyze this process, which is also facilitated by the development and maintenance of efficient channels of membership-wide communication.

Peter J. M. Nas, who became the next secretary-general, continued and expanded the publication of the newsletter and also developed an official website, which rapidly became the central point of contact for the Union.