Abstract: (Does Mother Tongue Influence New Language Adquisition? Ethnographic Study conducted in the Province of Castellon) To understand the language acquisition process we first need to start from the basis of knowledge that we possess in our own language, in our mother tongue, since the latter influences in the learning of other languages. The lack of scientific studies that focus on the language management each family possesses has prompted us to concentrate on the Romanian families that emigrated to Castellón (Spain) in the early twentieth century, one of the most representative communities of immigrants in this area. The aim is to examine the relationship between the mother tongue and the languages of the host society, where data were collected in several interviews that I have been carried out with the parents and children that make up the sample of participants through the observation and participation of the families. Thus, this work concerns the mother tongue and its use in the bilingual context of Castellón by taking the mother tongue as an instrument of intercultural communication in the classroom and outside of it, being at the same time a transcendental factor in the formation of a person’s identity in the sample of participants that make up the study. The parameters languages and cultures-context-individual will be examined in the light of the multilingualism and multiculturalism as the approach which addresses the diversity of languages and cultures, being the individual the main agent that gives meaning to this relation of parameters or perspectives.