ABSTRACT
The article analyses some general network mechanisms underlying the formation of social ties in order to argue that it is not only identity, cultural similarity or discrimination which creates clusters of people of the same 'origin' (in, say, friendship groups). Widely held assumptions about the logic underlying ethnic segregation are challenged and it is argued that migration itself leads to a re-organization of social networks which can produce marked separation of groups. Evidence is discussed from an Italian case of mass internal migration which has produced long-term ('second generation') effects in terms of stratification and schooling similar to many cases of international migration notwithstanding the absence of citizenship disadvantage and major cultural differences. This seems to illustrate marked network effects on many dimensions of 'integration'.
