12 Ethnic sorting in football membership rates – often on the basis of survey data – but these do not account for members’ respective club ties. Consequently, little is still known about how ethnic background is related to and impacts membership ties structurally. One major cause of this lacuna is the extensive and relatively complex data that are required. Namely, to truly study the relationship between ethnic background and club membership one needs to create a comprehensive overview of not only the membership base and members’ ethnic backgrounds - which is a challenge in itself - but also of all their respective club memberships. Additionally, to study anything at all, these data also need to be collected on a sport which enjoys a high popularity among a wide array of ethnic groups. When it comes to universal popularity, few if any sports can trump football. Virtually all over the world, football has a strong foothold in the organized sports domain and especially in many European countries football is unrivalled in terms of players and club memberships. The Netherlands is a case in point. With well over one million members spread over nearly three thousand clubs, no other type of sports club or civil society organization comes close to the pervasiveness of amateur football clubs in the social life of Dutch citizens. Amateur football clubs also seem to exert a strong appeal towards minority groups in the Netherlands. Evidence suggests they tend to rank football amongst the highest in terms of interest. Many clubs, particularly in urban areas, tend to have substantial shares of members with migrant backgrounds, which in some cases make up the whole member population. While we know many ethnic minorities find their way into amateur football clubs, the extent and way in which this happens, and its consequences for membership ties, so far have remained unknown. Luckily, over time, the quality and amount of membership data the Royal Dutch Football Association keeps, have significantly improved. Additionally, data on ethnic background in the Netherlands are well kept and accessible for research purposes. By combining these data, it has now become possible to gain a comprehensive and longitudinal overview of virtually all memberships of amateur football clubs and the ethnic backgrounds of their members. Consequently, this study seeks to combine these data and gain a better understanding of how ethnic background and membership are structurally related in the highly relevant context of Dutch amateur football. With this aim, I have formulated the following main research question of this dissertation: