One aspect of the compound of issues hiding behind the word -migration- is irregular migration, sometimes referred to as -undocumented-, -sans papier- or -illegal- migration. In this book the notion -irregular- is most often used as ideas about what is legal and illegal when it comes to migration are far from clear and also extremely politically volatile. The irregular migrant is, in fact, at the centre of one of the great paradoxes of European politics today: the openly declared demographic need for more labour and the strong consensus on a toughening migration regime, limiting the possibilities to enter regularly into the Union. This is linked to a growing concern about informalisation of the labour market and populist anti-immigrant mobilisation, gaining influence in many European countries today. The irregular migrant, although often forced to -play in the dark-, in real life as well as in the narratives of national and Union development, is however a key figure behind many central political discussions today. Therefore, to understand what is at stake for the migrant forced into the precarious situation of irregularity and for the communities and governments that are sending, receiving and sometimes deporting, sometimes turning a blind eye, the discussion must be connected to questions of globalisation, out-sourcing, welfare change, human-, migrants-- and workers- rights, as well as to long standing debates on multiculturalism, racism and anti-racism, diasporas and xenophobia in European communities. But experience, research and policy vary greatly across Europe. However, as migration is about crossing borders and (EU) policy, for some time now, has seeked solutions that transcend national borders, research and public discussion must do the same. This book is an attempt to assemble contributions from researchers across the EU, the new member states, selected candidate countries, some of the neighbouring countries in Eastern Europe, the Western Balkans and the Southern Mediterranean. Methodologically there is a great variety among the contributions, which is suitable since one hardly gets anywhere with a multileveled and complex issue like irregular migration without a multidisciplinary approach. This is also motivated by an additional ambition of this book to, beside bringing together different European experiences, also try to link better the otherwise often separate discussions on globalisation, labour market change, racism and xenophobia to migration, both irregular and regular. Hence, to study migration means opening for a discussion of political economy, development issues and large scale legal, social and political transitions, as well as local communities and networks, individual strategies of survival and personal fates, joys and tragedies. We have divided the book into five parts representing different aspects of this large topic.