This paper brings an insight into some elements of bilingual development - in Czech as a heritage language and in Croatian as the language of education and official language - among younger speakers who are members of the Czech national minority in Croatia, living in Daruvarski Brestovac. In the introductory part of this paper, basic theoretical knowledge about language development in children is presented. In the second part of the paper, bilingualism and bilingual development of speakers is presented in more detail. The continuation of the work (part 3) provides a brief overview of national minorities in Croatia. Special attention is focused on the Czech national minority in Croatia, so a brief historical overview on the Czech national minority in Croatia and their contribution to the development of the community and society is provided. The work is then narrowed down to the center of the Czechs in Croatia, the city of Daruvar. It describes the mentioned city and points to the state of Czech language, culture and customs in it, as well as in the surrounding area. A historical overview of two villages near Daruvar, Končanica and Daruvarski Brestovac, is presented, all with an emphasis on the Czechs and the development of the status of the Czech language. The school system and the frequency of the Czech language in kindergartens, primary and secondary schools are also described. A brief overview of the culture and customs that have survived to this day is also provided. The 4th part of the paper describes the experience of bilingualism of two girls, sisters - residents of mentioned area and members of the Czech linguistic minority. One of the girls is five years old, and the other is seven years old. Their reviews, attitudes and reflections on socializing and learning experiences (in kindergarten and school) in bilingual circumstances are presented. In the last, concluding part of the paper, the value of fostering bilingualism and preserving linguistic heritage, and thus the overall heritage of numerous generations of Czechs in Croatia, is highlighted.