From 1953 on, a party system of the European Union has been build up with, at the end, some 6 or 7 distinct and more or less cohesive parties acting in parliament and beyond. It has been said that this party system was “ready for power” during the 5th legislature of the directly elected European Parliament. In this article we ask whether and how Eastern enlargement has changed this state of affairs. The result of the empirical analysis is remarkably ambivalent: first, Eastern enlargement has increased the proportion of “homeless” MEPs, i.e. the non-aligned, and has at the same time added to the strength of the conservative majority of the house. Second, it did not significantly affect the format of the party system nor the stature of its political groups, neither their distinctiveness nor their cohesiveness. And third, the parties from the new Eastern member countries are not yet very well “rooted” in their national electorates. This is why the diagnosis of this early examination has to remain somewhat inconclusive – probably for some years to come
