The purpose of the study is to show how the activities of the Mennonite closed cooperative “Union of the Descendants of the Dutch” (UDD) were refl ected in the offi cial reports of Soviet offi cials; to analyze the importance of the organization for the consolidation of the ethno-confessional community of Mennonites in Ukraine. The research methodology: the general scientifi c (method of system analysis) and special historical (historical-comparative, historical-genetic, problem-chronological) methods are used. Scientifi c novelty: the study notes the importance of the “Union of the Descendants of the Dutch” in reviving and preserving the moral and ethical principles of the ethno-confessional group, and shows the organization’s infl uence on protecting the rights of national minorities in the Soviet state. Conclusions. In the conditions of the early Soviet rule, the economic decline of the region, the location of the Mennonite colonies, and the demoralization of the ethno-confessional community, the “Union” served to coordinate the life and preserve the traditions of the Mennonite communities. The fact that the organization was built on ethnic principles, existed with the help of foreign Mennonite centres (Germany, the Netherlands, the United States, Canada), and abandoned atheistic principles, caused great concern on the part of party, and administrative authorities. Feeling unable to adapt to new political conditions, the UDD led the Mennonite emigration movement of 1923–1926, which gained international notoriety and created a negative image of the Soviet state. The activities of the “Union” were under the supervision of the authorities since 1924. As the totalitarian systemin the USSR and increasing pressure on dissent, the authorities found an offi cial reason for the dissolution of the organization, which took place even in the policy of indigenization. As a result of the liquidation of the organization, the Mennonite population of the USSR found itself vulnerable to pressure from the authorities and shared the fate of the entire Ukrainian peasantry.