This paper investigates the intergenerational transmission of language capital amongst immigrants, and the effect of language deficiencies on the economic performance of second generation immigrants. Using a long panel that oversamples immigrants, we can follow their children after they have left the parental home. Our results show a sizeable significant association between parents’ and children’s fluency, conditional on parental and family characteristics. We find that language deficiencies of the second generation are associated with poorer labour market outcomes for females only. Finally, we find a strong relationship between parental fluency and female labour market outcomes, which works through the child’s language proficiency.