The main aim of this master thesis was to explore the conditions of growing up in bilingual families. The theoretical part of the paper describes, among other things, the process of acquiring the mother tongue and second language, whereas different types of bilingualism are presented within the elaboration of the concept of bilingualism. Particular emphasis was placed on aspects such as the role of parents in a bilingual family, the language mixing and the advantages and disadvantages of bilingual upbringing of children. An interview method was used for the purpose of collecting, whereas semi-structured type of interview was used as an instrument for obtaining the materials for the analysis. The study included 10 interviewees, 5 of whom were parents of bilingual children and 5 were children raised in bilingual families. In addition to the aspects listed above, the remaining analyzed aspects were: procedures to encourage the development of bilingualism in children and the influence of older siblings, as well as the influence of the wider family, in mother tongue transmission. Among other things, analysis of the interlocutors’ responses showed the following results: the role of parents in the process of planning a bilingual family is crucial, plus all bilingual children go through a language mixing phase. Furthermore, older siblings and wider family members help parents with mother tongue transmission and, finally, bilingual upbringing of children has more advantages than disadvantages.