The International Arthurian Society (IAS) was formed in the course of the second Arthurian Congress, which was held in Quimper in 1948 and which brought together scholars interested in Arthuriana from France, Britain, the Netherlands and the United States. Jean Frappier, the President, Roger Sherman Loomis and Eugène Vinaver took the initiative; all those present at the Congress were convinced that "the study of Arthurian literature and of the 'Matter of Britain', because of its broad reach and the variety of approaches and problems that it addressed, was beginning to constitute a distinct discipline, and that the time had come to coordinate the efforts of Arthurian scholars world-wide" (Jean Frappier, Bibliographical Bulletin of the International Arthurian Society (BBIAS), 1, 1949, p. 5).
The International Arthurian Society has three main objectives:
- The holding of triennial Congresses, largely devoted to the reading and discussion of scholarly papers.
- The publication of an annual Bibliographical Bulletin which lists all scholarly publications in the Arthurian field, and which allows members to keep in touch with the activities of the Society.
- The establishment and maintenance in Paris of an Arthurian Documentation Centre, consisting of a library and a collection of bibliographical material.
At the outset, the International Arthurian Society had three branches only: American, British and French. However, the second volume of the Bibliographical Bulletin, published in 1950, shows the creation of a Belgian branch; at this time, too, the future shape of the Bulletin was established by a division into three sections:
- Research and Criticism
- Arthurian News
Later, a fourth part would be added giving a list of members and their addresses. Finally, and progressively, German, Irish, Swiss and Spanish branches would be established.
Today, the IAS has eleven branches in all, having added Dutch, Hispanic (Brazilian, Portuguese and Spanish), Italian, Japanese, Scandinavian and Romanian; there are also corresponding secretaries in Finland, Hungary, Israel and Russia.
Since 1948, there have been sixteen international presidents:
- From 1948 to 1965: Professor Jean Frappier, University of Paris-Sorbonne
- From 1966 to 1968: Professor Eugène Vinaver, University of Wisconsin
- From 1969 to 1971: Professor Wilhelm Kellermann, University of Göttingen
- From 1972 to 1974: Professor Helaine Newstead, Hunter College, New York
- From 1975 to 1977: Professor Lewis Thorpe, University of Nottingham
- 1978: Professor Maurice Delbouille, University of Liège
- From 1979 to 1980: Professor Armel Diverres, University of Wales, Swansea
- From 1981 to 1983: Professor Charles Foulon, University of Haute-Bretagne, Rennes
- From 1984 to 1986: Professor Norris J. Lacy, University of Kansas
- From 1987 to 1990: Dr. Elspeth Kennedy, University of Oxford
- From 1991 to 1993: Professor Friedrich Wolfzettel, University of Frankfurt-am-Main
- From 1994 to 1996: Professor Anna Maria Finoli, University of Milan
- From 1997 to 1999: Professor Philippe Ménard, University of Paris-Sorbonne
- From 2000 to 2002: Dr. Jane H. M. Taylor, University of Oxford
- From 2003 to 2005: Dr. Bart Besamusca, University of Utrecht
- From 2006-2008: Professor Peter Field, University of Wales-Bangor.
- From 2009-2011: Professor Christine Ferlampin-Acher, University of Haute-Bretagne, Rennes
- From 2012: Professor Keith Busby, University of Wisconsin-Madison
International Congresses have been held as follows: