Michael Bommes was one of the most innovative and profound theorists of immigration and integration of our time. His work drew on the systems theory of Niklas Luhmann to develop a highly compelling and sophisticated alternative to predominant contributions in migration studies. His writing constantly questions and challenges mainstream theories and concepts in migration studies, from notions of assimilation and transnationalism, to multiculturalism and discrimination, irregular migration and migrant networks. But equally important is his attempt to advance sociological research through the lens of immigration. His repeated assertion is that immigration has had major consequences for modern social systems and welfare states, and that understanding these impacts needs to be a central question not just for migration scholars, but for sociologists more generally.

Through his research, teaching and policy work, Bommes earned himself a dedicated following, especially across Europe. However, we feel that his work deserves an even wider audience. One of the impediments to achieving a broader impact is that much of his work has been published exclusively in German or in outlets that are not widely disseminated outside of German-speaking countries. Michael's tragic and untimely death in 2010 also meant that he never had the opportunity to collect the different strands of his opus into one collection.

This book therefore brings together what we believe is a representative sample of Bommes’ most important work on migration and integration. It includes a number of articles or chapters that are appearing in English for the first time, as well as articles that were published in German outlets. The book starts with a series of four chapters on immigration, social systems and the modern welfare state, one of the core themes of his work. Two chapters follow on immigrant integration, with subsequent chapters dealing with, respectively, illegal migration, networks and migration research. In this brief introduction, we start by setting out some of the key themes of his work and introduce the nine chapters. In a second part, we say something about Bommes’ academic career and his work with students and practitioners.

Bommes was particularly gifted in bridging applied themes in migration research with broader theoretical questions in sociology.