This book includes a selection of papers written in the last ten years (2009-2019) in affiliation to Swiss academic institutions. They have been updated and edited for this publication. The idea behind the present collection is to make full value of comparative research carried out both from a theoretical or empirical perspective on different categories of migrants from the elderly to second generation and from low to highly skilled, originating from a variety of regions and geographical contexts. They come from the Sub-Saharan African region as well as Western and Eastern Europe presently living on the European continent. Paolo Ruspini is a political scientist who has been researching issues of international and European migration and integration since 1997 with a comparative approach and by drawing on mixed methods. His current research deals with transnational migration from a theoretical and empirical perspective.