50 Ethnic sorting in football voluntary associations serve as important organizational settings to connect to others outside the family structure (Louch, 2000), these organizations tend to be marked by socially homogeneous compositions favouring the production and preservation of homophilic ties (McPherson, 1983). Therefore, we may be directed to expect that the landscape of voluntary associations is rather ethnically segregated, severely constraining the meeting and bonding opportunities with outgroup co-members. Surprisingly, barely any studies so far have looked at ethnic homophily in voluntary association membership on a large scale (Wiertz, 2016 is a notable exception). A number of sports sociological studies have explored links between ethnicity and sports participation quantitatively, but it remains unclear how and/or with whom these activities are organized (e.g. Breuer & Wicker, 2008; Higgins, 2013; Van Haaften, 2019). Furthermore, McPherson and his colleagues have demonstrated a positive relation between membership and shared similarities with co-members, but ethnicity was not included in these analyses (McPherson & Rotolo, 1996; Popielarz & McPherson, 1995). Moreover, even when voluntary associations might produce homophilous co-membership ties in general, McPherson (1983) notes that different types of voluntary groups can vary strongly in the forms and degree of homophily they induce. An important distinction can be made between voluntary groups organized around activities which enjoy interest by a selective pool in general population and voluntary groups organized around activities which share a wide interest across different social strata. The first type induces homophily due to a selective interest, while the latter induces homophily when the total member population distributes unequally over groups. I would argue that this latter case is a particularly fruitful area for research on homophily because it can direct us to potential sorting mechanisms with a broader relevance. This study therefore aims to further explore ethnic homophily in membership of Dutch amateur football clubs and its development over roughly a decade. The Netherlands is estimated to have both the highest share of club-based sports activities (23%), and the highest membership rate (27%) of Europe (Eurobarometer, 2014). Of these voluntary sports organizations, amateur football clubs are by far the most popular, accommodating well over a million members nationally. Moreover, earlier studies have shown that amateur football, unlike various other organized sports, enjoys a wide interest and high participation rates across various ethnic minority groups (Elling & Knoppers, 2005; Van Haaften,