Studies of migrant transnationalism are dominated by qualitative case studies. To take the field further, there is a need for more quantitative studies and for connecting quantitative and qualitative studies through a reiterative feedback loop. In order to contribute to this, we take two refined and original quantitative studies, one by Snel, Engbersen and Leerkes and one by Portes et al., as a vantage point, commenting on the authors’ organization of analytical categories and their operationalization of key concepts, in light of our own, qualitative data. This data comes from a research project, EUMARGINS, where we analyze processes of inclusion and exclusion of young adult immigrants and descendants in seven European countries, using participant observation and life story interviews in combination with statistical data. We conclude that the process whereby young migrants identify themselves in terms of ethnicity and belonging is context-specific and multidimensional, and hard to study quantitatively.