This article reports on some data of a psycholinguistic study of first language attrition in german first generation immigrants. On the basis of the individual variation in performance evidenced by the data, I claim that L1 attrition in late bilinguals is not only the consequence of lack of L1 use. A comparison of the performance of three selected German-English bilinguals rather suggests that, among other factors, contact with other immigrants – as is the case in immigrant communities – might generate changes in linguistic competence. In this case it would be necessary to distinguish to types of intra-generational L1 attrition: (a) attrition in isolated immigrants who never use L1 in the host country, which mainly yields processing difficulties and problems in lexical retrieval, and (b) attrition in members of immigrant communities where changes of the linguistic norm within the community can take place, resulting in modifications of linguistic competence.