Expanded employment opportunities acrossthe continent have been one of the most significant changesto have taken place in Europe during the past 50 years.Since the inception of the European Economic Community in1957 involving 6 countries (Belgium, France, Italy,Luxembourg, the Netherlands and West Germany) with acombined population of less than 200 million, the EuropeanUnion (EU) has grown to encompass nearly 500 million peopleacross 27 member countries that produce, in total, about 30percent of the world's total gross domestic product.May 2010 marked the six-year anniversary of the inclusion ofeight countries from Central and Eastern Europe (CzechRepublic, Estonia, Hungary, Latvia, Lithuania, Poland, theSlovak Republic and Slovenia) into the EU, followed byRomania and Bulgaria in January 2007. An importantconsequence of these 10 new member states (henceforth EU10)joining the EU has been to expand the internal EU labormarket, albeit to varying extents for nationals of differentmember countries. Migration flows out of the EU10 followingthe 2004 enlargement is hampered by various technical anddata constraints. As a result, the policy debates on thewelfare consequences of migration following enlargement forboth the host and sender countries have often been based onspeculation and ideology rather than on the empiricalevidence per se. Following the accession of EU10 countriesto the EU, how large were the ensuing flows of migrantworkers, and what were their main socio-economiccharacteristics?-in particular, how do migrants from withinthe EU compare to those from countries outside the EU? Aremigrants poorer than the native-born population?-do theyimpose a high economic and social burden on the countrieswhere they currently reside? Addressing these and other suchkey issues of policy interest are among the main questionsaddressed by this report. Using information from a varietyof data sources, it takes stock of the nature, extent, andimpact of EU migration following EU10 accession, andsynthesizes the main lessons from this experience for futuremigration policy. In particular, the report highlights thepositive contributions made by migrants in their hostcountries, as well as documents the growing importance ofremittances in receiving countries.