The importance of investigating the family language policies within multilingual families living in Luxembourg is primarily based the trilingualism that characterizes Luxembourg, the heterogeneity of its population, problems faced by immigrant children schooling in Luxembourg’s school and individual’s personal experience with everyday language use as well. Hence, this thesis’s aim is to investigate how parents from different linguistic backgrounds or having the same language of origin communicated with each other prior to the birth of their children and how the birth of these children reshapes the family language environment. Specifically, we aim to understand the parents’ motivations with regard to their language choices and the communication strategies they implement in order to establish a family communication environment. In addition, considering the effects of language contact, we focus on the school languages and their influence on the children’s language at home. In order to achieve this, from a methodological point of view, by combining ethnographic interviews with the recordings of a family conversation, we gained access to the declared and real linguistic practices of ten families with highly diverse linguistic profiles. These families reside between seven and forty-two years in Luxembourg. Further, content analysis was used to examine the migratory experience of each parent. Some of the major reasons why parents adopted a positive attitude towards multilingualism were (a) the language learning and use opportunities offered by Luxembourg and (b) the desire to develop the linguistic capital of their children. Our results later suggest that although children do not participate actively in the language use decision-making process they actively influence the family language environment. Because the languages they learn in school impact the ways in which they speak at home. Moreover, we discovered that once these children have contact with the officially recognised languages in Luxembourg, which might be ...