Introduction: Notwithstanding the political climate in Europe—uneasy because of new inflows of (illegal) asylum seekers from countries such as Northern Africa, of legal immigration from Eastern Europe, and of ongoing family formation migration—it remains amazing that research in this field continues to be an intellectually interesting and productive field, even in a period in which funding is more difficult. Again, this issue includes contributions from different countries covering different European regions. The field remains challenging because of several reasons. ...