Lexical access and lexical diversity are often assumed to be vulnerable to first language (L1) attrition. They also differ between monolinguals and nonimmersed bilinguals. This raises the question whether lexical attrition can be ascribed to nonuse or to competition between the two languages. We compare two populations of late L2 learners of Dutch living in the Netherlands. One of them was largely monolingual prior to emigration (Turkish migrants), while the other comes from a highly multilingual society (Morocco). While both experimental populations should be affected by erosion due to nonuse, we expect competition effects to be more strongly pronounced when compared against a monolingual versus a multilingual baseline population. The results show that this is not the case with attrition effects being even stronger in the Moroccan group than in the Turkish group. Furthermore, there is no impact of individual measures of frequency of exposure or language attitudes among the attriters. We conclude that being immersed in an L2 environment leads to weakening of lexical access.