Catalonia (Spain), this paper intends to analyse the impact of the family language and the generational cohort on the language attitudes towards Catalan and Spanish that is built by immigrant children (aged 14-16). The nature of the analysis carried out as a result of an attitude questionnaire answered by 527 young people allows differentiation of the effect of both variables individually when included in the same explanatory model. Results indicate that being Spanish-speaking or non-Spanish-speaking is influential in the construction of attitudes towards Spanish and towards Catalan. Moreover, the generational cohort is only influential for attitudes towards Catalan and when a migratory transit has been experienced or not. Since both variables are included in the same model, it is suggested that the effect of the generational cohort is moderated by being Spanish-speaking or not. The new perspectives opened up by these results are discussed as regards the promotion of intercultural communication and a common project of coexistence.