Enlargement today is a priority on the European agenda. Examining Portugal and Greece from a comparative perspective with respect to Poland, this Study analyzes the original and specific paths each of these national configurations have taken as regards administrative and institutional changes, particularly through the regional dimension, policy reorientations and modes of government. Given the large body of acquis communautaire that must be integrated, the nature of Commission involvement and the highly regulatory nature of European directives, this dimension emerges as the most significant in the process of Europeanization: public administration acts as a filter in this dynamic and nation-states are paradoxically strengthened by European integration. This comparison is an opportunity to underscore the importance of innovations and the singularity of modes of government, suggesting that certain arrangements put into practice in cohesion countries may provide sources of inspiration for the new entrants, which are faced with similar problems of administrative competence, bureaucratic blockages and political and state legacies that are remote from the European model of public administration, civil service organization and rules. With the effect of European constraints, a threefold dynamic is at work: a dynamic of delegation, or privatization, through the creation of agencies, offices and institutes, a dynamic of politicized (re)centralization, and a dynamic of political, institutional and social innovation. Thus components of these models are constantly borrowed and reshaped, hybrid constructions are formed and configurations take shape that are no less European than what can be found in the “heart” of Europe.