Large-scale immigration, which resulted either from the processes of decolonization or from labour migration, led to the development of new ethnolectal varieties of Dutch. Following a brief discussion concerning the definition of this notion and a modest survey of the relevant literature (both international and for the Dutch situation), a rough demographic sketch of the present-day situation of ethnic minorities in The Netherlands will be presented. Next, a large ongoing research project into the emergent Moroccan and Turkish ethnolectal varieties of Dutch in two major cities will be introduced. This project targets at answering three different sets of questions regarding ethnolects. One set of questions concerns the linguistic makeup of ethnolects: to which extent are they rooted in substrates, in phenomena that are typical of second language acquisition and in endogeneous non-standard varieties? Another set of questions concerns the place of the ethnolect in the verbal repertoires of its speakers. Yet other questions concern the spread of ethnolectal features to other ethnic groups. It is argued why the three sets of questions all emanate from a language-centered rather than an ethnographic approach to ethnolects. After a sketch of the methods and design as well as the resulting database, some first findings will be presented regarding a particular non-indigeneous feature in the province of phonology, discussing its nature, probable origin, use and incipient social spread. For this contribution the use of the feature has been analysed in conversational speech of a small subset of the subjects in the research design in a range of interactional situations; the analyses zoom in on several different dimensions in the distribution of the feature. The findings for the micro-social dimensions studied partly bridge the seeming gap between quantitative (Labovian) approaches to language variation on the one hand and qualitative, partly interpretive (Gumperz-type) approaches on the other. There appear to be interesting and highly plausible relations between the quantitative patterns in the subjects’ use of the feature and several mutually related aspects of the interlocutor’s background. This leads to a discussion of the stylistic meaning of these patterns and of ethnolectal variation in general. Finally it will be argued that international research cooperation could greatly help to unravel internal, external and extra-linguistic forces underlying the development and use of these new non-standard features as well as their diffusion to the verbal repertoires of other cultural groups.