This paper applies the concept of trade creation and diversion to immigration into the EU-15 in the 1980s and 1990s. In particular, the 1990s process of East-West integration, culminating in the May 2004 enlargement, could potentially create immigration from the new member countries and at the same time divert migration from non-EU countries. In this context, the question this paper tries to answer is fundamentally whether the extension of the EU Single Market to the new member countries has the potential to crowd-out non-EU immigrants. The analysis is carried out using trend analysis, Truman shares, and panel data gravity models. The results are quite robust to a range of regression methods, model specifications, dependent variables, and time periods. They broadly support the migration creation hypothesis, but the evidence on the migration diversion hypothesis is mixed. There is evidence of some diversion away from other non-member European countries, such as ex-USSR and ex-Yugoslavia countries, in favour of the new Central and Eastern European members. However, the evidence of diversion away from non-European countries is much weaker, if at all existent. The high impact of a common language, when compared to distance or even a common border, may help preserving migration channels from outside Europe. Within Europe, shorter distances and common borders become more relevant.