The organizing meeting was an international congress of Yiddish culture, the first to be held since the 1908 Czernowitz Conference for the Yiddish Language; about 100 delegates attended, including 11 from the United States. The first chairman of YKUF was the non-Communist writer Alexander Mukdoni; the secretary (to 1957) was the poet Zishe Weinper, an efficient fundraiser for YKUF and, according to Melech Epstein, a "secret member of the Communist Party." In the U.S., financial support also came from the Jewish People's Fraternal Order, the Jewish section of the International Workers Order. At the time of the non-aggression pact between Joseph Stalin and Adolf Hitler in August 1939, many of the non-Communist artists and writers affiliated with YKUF left the organization.