Superdiversity a concept or a theory?

The concept ‘Superdiversity’ developed by Steve Vertovec has been one of the most cited and discussed concepts in the field of migration and ethnic studies in the last fifteen years. This is remarkable given that it is a concept and not a full-blown theory like Segmented Assimilation (Portes and Zhou, 1993) or New Assimilation theory (Alba and Nee, 2003). The concept clearly filled an important void experienced by researchers working on a wide variety of topics in city contexts that absorbed a lot of new migrants over a relatively short period of time. I was asked to write this review about Vertovec’s new book Superdiversity, and, in an act of total disclosure, I want to alert the reader that I have been using the concept of superdiversity myself for over a decade and have written several articles and books using it. So, I am part of a very large crowd of promotors of Vertovec’s concept. At the same time, I also have been somewhat critical of the vagueness of the concept. I have especially been trying to formulate when to use it and also proposing in which way the concept can help us to explain societal processes in superdiverse contexts (Crul, 2016).