The aim of the thesis is to outline the development and evolution of mass non-European immigration into EU selected member states and to analyze the effect it has had, it has and it might have on their societies and economic development. The member states chosen are basically the ones that are mostly affected by this phenomenon which immigration is. These are: UK, France, Germany, Netherlands, Italy and Spain to some extent. The timeframe has been chosen from World War II till present days, since although immigration appeared on EC agenda during the 1980s, the willingness and openness as well as the need of non-European mass immigration have started with the reconstruction of postwar Europe. The reasons behind this are numerous and the goal is to describe and analyze them in the thesis. The author is going to point out the economic factors and how they changed over time; the role colonialism has played, as well as the moral aspects that have led to immigrants coming to Europe’s most advanced member states. Apart from that, the thesis will examine as to why non-European immigrants were and are necessary, to what extent and how their numbers have increased throughout the years. It will try to analyze if this increase in numbers has been positive or negative, and how do the societies of the member-states examined accept immigrants into their communities, do they manage to integrate, and if not why? Another aspect the thesis will tackle is the emergence and evolution of the Common European Union Immigration Policy; the author will show why EU needs it and how important it is for the well being of the Union. And finally how governments can cope with the challenges immigration possesses because although welcomed the increasing numbers of immigrants are becoming one of the top 10 preoccupations of European citizens, so is immigration a challenge or an opportunity, or may be both? Bibliography: 1. “An opportunity and a challenge. Migration in the European Union”. Luxembourg: Publications Office of the European Union, 2009 2. “Immigration, Asylum and Social Integration”. Luxembourg: Publications Office of the European Union, 2002 3. “Nationalism Reframed: Nationhood and the National Question in the new Europe”. Cambridge University Press, 1996 4. Brady, Hugo. “EU Migration Policy. A-Z”. London, Center For European Reform, 2008 5. Caldwell, Christopher. “Reflections on the Revolution in Europe”. Penguin Books, 2010 6. Huntington, Samuel. “The Clash of Civilizations and the Remaking of World Order”. New York, 1996 7. Legrain, Philippe. “Immigrants. Your country Needs Them”. London: Little Brown, 2006 8. Panayiotopolous, Prodromos. “Immigrant Enterprise in Europe and the USA”. Routledge, 2006