28 Ethnic sorting in football similar to, and inspired by Dronkers and Van der Velden (2013): 1) Northern/Western/Southern European and Anglo-Saxon, 2) Middle and Eastern European, 3) North African and Muslim Asian, 4) Sub-Saharan African, 5) NonMuslim Asian and Oceanian (excluding Australia and New Zealand) and 6) Middle and South American. A detailed list of all countries making up these six categories can be found in Appendix A. To determine an individual’s ethnic background, I follow the operationalization procedure which is customary for Statistics Netherlands and Dutch academic researchers. This means that if somebody has two parents who are both born in the Netherlands, this person is considered ethnically Dutch5. If someone has at least one parent who is born outside of the Netherlands, this person is believed to have an ethnic minority background. If the individual is born outside of the Netherlands, the ethnic background is determined by the official country of birth (e.g. a person who is born in Turkey and has one or more parent who is born outside of the Netherlands will be considered to have a Turkish background). If an individual is born in the Netherlands, the country of birth of the parents is used to determine his or her ethnic background. In these cases, the country of birth of the mother is used over that of the father, unless the Netherlands is also her country of birth (e.g. a person who is born in the Netherlands with a mother born in Turkey and a father born in Morocco will be considered to have a Turkish background). Club Membership An individual is considered a member of an amateur football club when he or she is registered as a member at a club during the playing season. A playing season was measured as beginning on 15 August of a certain year and ending on 15 May of the following year. People who were registered as a member at a club after 15 May but terminated their membership prior to 15 August were left out. 5 Consequently, only first and second-generation minorities are included. Third generation minorities are categorized as ethnically Dutch in population statistics. While it could be argued that classifying this group as Dutch is problematic, explorations on the third-generation population indicates that this group is still very small and young for most backgrounds. Additionally, focusing on the first and second generations ensures the existence of a migration experience within the family while also preventing that individuals remain ‘strangers’ (Thiel & Seiberth, 2017) forever.