Designed to organize the social redistribution between sedentary members of solidaristic community of the Nation State, Welfare State is by nature closed. Its boundaries prevent entry of non-members and render difficult exit of members. The case law which associates European citizenship with principles of freedom of movement and equal treatment prohibits, without justifications, national and residential criteria as conditions of access to Welfare State’s benefits, entailing then the denationalization and the deterritorialization of social systems of the Members States. Nevertheless, some form of closure has to be granted to Welfare State to preserve its specific foundation and function. The “real links” became the main tool to regulate relations between migrants and the Member States as regards access to social benefits. Based on concept of integration, “real links” criterion demonstrates effort to reconcile the opposite interests in this field.