The European political map has been constantly changing since the World War II. The Czechoslavakia and Yugoslavia dissolved, Germany reunited and the European Union (EU) has been expanding. The original European Economic Community (EEC) has grown from 6 to 27 members and the process has been on-going. Enlargement is a permanent and continuous item on the EU agenda and by far one of the most speculated policies. Enlargement policy aims at preparing the countries concerned to become full members of the EU when they, as well as the EU, are ready. Therefore, EU has provided a well-designed institutional framework for enlargement. Nevertheless, it doesn't necessarily mean that EU enlarges only. Even though United Kingdom's (UK) EU departure represented the sharpest challenge of recent times, the cases of Algeria, Greenland and Saint Barthélémy had shown that withdrawal from the EU and the institutions that preceded it, was not an absolutely new phenomenon. The objective of this article is to depict and to compare the institutional framework and the historical background of the enlargement and withdrawing facts. A discussion of theorization falls outside the scope of this illustrative paper and it is just aimed to provoke thinking.