In the Croatia territory, the Czechs are concentrated predominantly in the area of the northwestern Slavonia. Center of this region with relatively compact Czech settlement is the town of Daruvar. Before and after the World War I, when the Czechoslovak Foreign Institute and the National Czechoslovak Council were established, the interest in this region increased. In 1930’s the Czechoslovak Foreign Institute initiated a mapping survey of this region, which was, however, not completed. The further initiative was launched several decades later. A research of culture of the Czech colony in the Daruvar region was carried out in 1965-70 by the Ethnography and Folklore Institute of the Czechoslovak Academy of Sciences (ČSAV) and the Folk Art Institute in Zagreb. More recent works devoted to the Czechs living in Croatia originate primarily in the country itself. My research in the region was realized above all in the form of interviews. I received a lot of necessary information from the Czech Union archives and from the local professional literature. In comparison with the previous research and with respect to the several-decade distance, it was possible to trace the process of acculturation and assimilation and to estimate its possible development. The accessible printed materials and literature are of miscellaneous origin. they partly come from the Czechoslovak Foreign Institute employees - Antonín Šembera, Rudolf Turčín and Jan Auerhan. Many valuable documents are deposited in the Central State Archive in Prague, in the Ministry of Foreign Affairs archive as well as in the Náprstek Museum’s archive. A rich archive is situated in the seat of the Czech Union in Croatia - in the Czech House in Daruvar. It contains many documents from the life of the Czech minority. The collections in this archive were assorted with the help of the Czech Republic, that is to say by archivists from the Central State Archive in Prague who had been working here for several years since 2001.