The original precursor of the IAVS was founded in 1939, as the International Phytosociological Society (IPS), with headquarters in Montpellier. The IPS was re-established after the War, eventually as the Internationale Vereinigung für Vegetationskunde (IVV), which established itself more formally in 1954, at the International Botanical Congress in Paris, by adopting a constitution. The IVV served mainly German-speaking Europe and began holding international symposia at first Stolzenau and later Rinteln almost every year from 1956 to 1981.