The initial enthusiasm of many EU citizens at the 'return to Europe' of former members of the Soviet bloc has turned to anxiety at the realization of the possible adverse consequences of enlargement. Potential undesirable effects of enlargement, in particular for labour markets and social conditions, can be met by appropriately designed policies which are so far not in place or planned. Rather than legitimizing such fears, politicians and policy-makers must dispel them by leading the EU and its members to adopt these measures. Enlargement also offers the EU a window of opportunity to accelerate unavoidable reforms of structural policies, agricultural policies and their financing. These are the premises of this new CEPR Policy Paper. The authors outline the key economic and social implications of the prospective accession of the Central and East European countries into the European Union and propose policy recommendations for EU enlargement.