The framework of this article is the European Union statement “Together in Diversity” and the involvement of several states and people in a project of European integration, which combines the national and the community interests, in a perspective of cohesion and development. Three events occurred in 2007 - Celebrations of the 50th anniversary of Rome Treaty – Portuguese Presidency of the European Union – European Year of Equal Opportunities for All – were the near factors that contributed or writing up this text.
Within the scope of the 50 years of the EU, an overview of the historic antecedents and principles which carried out its foundation is given and, later on, of the evolution observed with the successive enlargements, as well the repercussions, meanwhile occurred, in the institutional and operational levels of the European integration. The synthesis of this evolution is followed by statistical data concerning the resident population, in a global
of the EU organization, in their several phases. Along these years, the characterization is processed through the changes of resident population, territory and population density.
In spite of great heterogeneity of the present 27 Member States in the relevance of the non-nationals residents, dependent in large part of the economic and social development level, it is generality checked in each country an increase of foreign people. The European Union is an attractive space for millions of people all over the world. However, the weight of the migratory flows among the Member States should not be ignored and it will be developed in the next Review number.

key words: enlargements, member-states, non-nationals, third countries, foreign population, population by citizenship, population by country of birth, population change.