IIA would meet together in Portugal in 1930 under the joint name Congres International d’Anthropologie et d’Archéologie Préhistorique. Not many prehistorians took part in this consolidation, however, because most were still unhappy about what they considered to be the still minor role allocated to prehistoric archaeology.

Later in 1930, the so-called committee of five (archaeologists gerhard bersu, R. Lantier, Obermaier, W. Unverzagt, and Bosch-Gimpera as secretary) met in Berlin to discuss the organization of international congresses devoted exclusively to prehistoric archaeology, which would convene on a truly international level and without any exclusions whatsoever. This idea was finalized in Bern, Switzerland (27–29 May 1931), and the new organization took the name Congres International des Sciences Prehistoriques et Protohistoriques (CISPP).

Some 500 scholars attended the first congress of the CISPP in London in August 1932 under the presidency of Sir Charles Peers. A.W. Brogger and john l. myres were both secretaries-general of the CISPP, and vere gordon childe, christopher f.c. hawkes, H.S. Kingsford, and C.A. Ralegh Radford were secretaries of the organizing committee. Archaeologists from thirty-five different countries formed a new Permanent Council.

The second congress was organized in 1936 in Oslo. Again, some 500 archaeologists attended its meetings, but the political climate of the time made for some unpleasantness. The proposal to hold the third congress in Budapest in 1940 was accepted, but the beginning of World War II intervened. After an abortive attempt to hold the congress in Budapest in 1949, the third congress finally met in Zurich in 1950. The absence of scholars working in eastern Europe undoubtedly explained why only some 250 prehistorians attended. On this occasion, the Executive Committee was created, with E. Vogt as its (provisional) secretary. In 1952, he was replaced by S. De Laet as secretary-general of the Executive Committee.

In 1954, the fourth congress took place in Madrid, and once again some 500 prehistorians attended, with colleagues from fifty-one countries being elected to the Permanent Council. It was decided that adherence to the Conseil International de la Philosophie et des Sciences Humaines (CIPSH) would make it possible to obtain financial help from the United Nations Educational, Scientific, Cultural Organization (UNESCO) for some of the scientific initiatives proposed by the congress. This affiliation to CIPSH (September 1955) made it necessary once more to change the name of the organization, this time to Union Internationale des Sciences Prehistoriques et Protohistoriques (UISPP, International Union of Prehistoric and Protohistoric Sciences).

The next congresses all saw a steady growth in the number of participants—which reached a peak in Nice of some 3,500 in 1976—and a corresponding growth in the number of members elected to the Permanent Council, which today has some 250 scholars working in nearly 100 countries. The next congress venues were as follows: fifth congress (1958), Hamburg; sixth (1962), Rome; seventh (1966), Prague; eighth (1971), Belgrade (this congress was the first to be organized five years after the previous one in accord with UNESCO’s five-year rule for major international congresses); ninth (1976), Nice; tenth (1981), Mexico City; eleventh (1987), Mainz.

The original venue in 1986 (Southampton-London) was changed to Mainz by a vote of the Permanent Council because the executive of the United Kingdom organizing committee had decided in late 1985 not to allow scholars active in South Africa to participate in the congress. This decision could not be accepted as it was contrary to the statutes and the tradition of the UISPP. Also, the decision was made without consulting either the Permanent Council, the Executive Committee, or the secretary-general of the UISPP. The meeting in Southampton took place under the title world archaeological congress (a change of name that had also been decided without any previous consultation with the UISPP executive), and this meeting repeated the error of the ill-fated Institut International d’Anthropologie, which in 1921 refused, for purely political reasons, to admit to its meetings scholars from Germany, Austria, etc. The decision by the Permanent Council and the