The free movement of workers is a fundamental right guaranteed by the Treaty on the Functioning of the European Union (EU). Therefore, EU citizens are entitled to look for a job in another EU country; work there without needing a work permit; reside there for that purpose; stay there even after employment has finished and enjoy equal treatment with nationals in access to employment, working conditions and all other social and tax advantages. But how many EU citizens take advantage of this right, and reside and work in another EU Member State? Which are the main countries, both in absolute and relative terms? What are the characteristics of these "mobile" citizens, especially in terms of level of education and employment rate, if we compare them with the "non-mobile" EU citizens (those residing in their country of citizenship)? These are the main questions which this article tries to answer, based on Eurostat's (new) datasets on labour mobility.