Although there is a common belief that more footballers are representing another country than their native ones in recent World Cup editions, a historical overview on migrant footballers representing national teams is lacking. To fill this lacuna, we created a database consisting of 9.400 football players who participated in the FIFA World Cup (1930-2014). In order to count the number of migrant footballers in national teams over time, we critically reflect on the term migrant and the commonly used foreign-born proxy in mainstream migration research. We argue that such a foreign-born approach overlooks historical-geopolitical changes like the redrawing of international boundaries and colonial relationships, and tends to shy away from citizenship complexities, leading to an overestimation of the number of migrant footballers in the database. Therefore, we offer an alternative approach which, through historical contextualization with an emphasis on citizenship, results in more accurate and reliable data on migrant football players. We coin this the contextual-nationality approach.