This study investigates the relationship between identification with the local territory, language attitudes and language proficiency in young immigrants in Catalonia, a region in Spain. The aims of the study are to examine how identification with the local territory affects attitudes and proficiency in languages, and whether language attitudes have a mediating effect on these relationships. The study used a sample of 543 students from the three main immigrant groups in Catalonia. Multigroup path analysis was performed. The results showed that identification with the local territory favoured attitudes to, and proficiency in, the language associated with that territory while disadvantaging the other language. However, the effect that identification with the local territory had on the level of language proficiency depended on the mediating effect of language attitudes. These findings help to explain why young immigrants' acquisition of language proficiency varies, and they highlight the facilitating or attenuating roles in the process of language acquisition of identification with the local territory and language attitudes.