The International Congress of Onomastic Sciences is a large conference held every three years and organised by members of ICOS. The next Congress will be held in Helsinki (Finland) in 2024.
- Paris 1938
- Paris 1947
- Bruxelles 1949
- Uppsala 1952
- Salamanca 1955
- München 1958
- Firenze 1961
- Amsterdam 1963
- London 1966
- Wien 1969
- Sofia 1972
- Bern 1975
- Kraków 1978
- Ann Arbor 1981
- Leipzig 1984
- Québec 1987
- Helsinki 1990
- Trier 1993
- Aberdeen 1996
- Santiago de Compostela 1999
- Uppsala 2002
- Pisa 2005
- Toronto 2008
- Barcelona 2011
- Glasgow 2014
- Debrecen 2017
- Kraków 2021
- Helsinki 2024
The proceedings of each Congress up to and including no. 26, have been published.