The article, based on the results of an empirical sociological study, examines the changes in the national identity of Bulgarian citizens under the influence of active migration processes within the EU. The started process of formation of su- pranational/European identity is substantiated. The exceptional dynamics of contemporary social processes, mass migratory movements in a world where borders are becoming more open and even practically absent (within the EU), and huge distances are covered in a very short time lead to significant changes in the identity of the Bulgarian citizens. New types of identity appear that are structurally and functionally different from the pre-existing ones, corresponding to the previous axiological paradigms. Constant process of movement from one society to another, and in particular from the new EU member states to the old member states within the “liquid migration”, leads to the transfer, assimilation and reconciliation of ideas, perceptions, understandings, values and behaviors that are typical for different societies, social groups and cultures. Bulgaria and Bulgarian citizens have been involved in these processes for three decades, with a gradually increasing intensity. Today the Bulgarian national identity is in constant transformation - the Bulgarian citizen becomes a European citizen, a citizen of the world. Thus, the specificity of social development logically leads to the formation of a supranational identity. On the other hand, when the change becomes permanent feature of society and radical changes occur over extremely short periods of time, it creates prerequisites for dissonance of identity. And sometimes, instead of the formation of a supranational identity, reverse processes of closure, localization, and regionalization are observed. It can be said that in modern Bulgarian society, the processes of European integration are accompanied by opposite processes of “atomization” of society and the “closure” of people into smaller, than national communities. The results of a national representative survey show that at this stage of development of the Bulgarian society, identification with the nation-state remains a key for Bulgarian citizens - more than half of the respondents identify themselves as citizens of Bulgaria. Almost one third of Bulgarian citizens, however, identify themselves with supranational structures (“citizen of Europe” and “citizen of the world”), which is an illustration of the processes of the formation of a supranational identity that have begun. And the identification of about one tenth of the respondents with their hometown, with the place where they were born, reflects the opposite trend of formation of local identity.