Immigration and multiculturalism are at the heart of modern Western societies. The issue of language acquisition of immigrants is intrinsically linked to immigration. We formally link language acquisition of immigrants to the relative size of the immigrant stock, employing a microeconomic trading framework. Our model allows for spatial interaction going beyond the immigrant's area of residence, and explicitly incorporates spatial segregation. In addition, behavioral differences of immigrants with respect to their level of assimilation into the host country, as well as differences in networking within their own ethnic community, are accounted for. We test our model for four non-Western immigrant groups in the Netherlands at two different spatial scale levels. The empirical results reveal that there is only ambiguous support for the inverse relationship between size of the immigrant community and language acquisition or language proficiency in The Netherlands. We find instead that there is strong support for language acquisition and understanding being positively influenced by assimilation to the host country's culture.