The Bachelor thesis comprehends how to coordinate the social security system within the European Union, that it isn't subject to unnecessary barriers of free movement. The first part will mapp of social security from the Middle Ages to the present and further work aims to coordinate, its principles and means of implementing the various components of social security and coordination in the course of practice. The second part will be devoted to specific social security systems in selected countries. Countries, whose social welfare work will be addressed, are Belgium and the Czech Republic. States were selected based on their position in the EU, where Belgium represents one of the founding members, while the Czech Republic is cited as an examp...