Methodological nationalism restricts the focus on transnational migrants in Europe, in particular in the Upper-Rhine border area (France-Germany-Switzerland). Three main limitations can be underlined: to start with, the ignorance of nationalism in contemporary social science research, including in migration and border studies; moreover, the naturalization of the nation- state that contributes to shape numerous social science biases; finally, territorial limitations that constrain research topics (Wimmer and Glick Schiller 2002). To overcome those issues, this research combines three methodological perspectives: first, a socio-historical analysis of transnational migrants in the Rhineland area, in order to comprehend past and contemporary dynamics; second, a socio-political approach that stresses the migrants "ways of being" (Glick Schiller 2005), including their activism and rhetoric, e.g. direct observations and interviews in multiple sites; third, a pluri-scalar approach that implies several levels of analysis, e.g. local, regional, cross-border, transnational and supra-national. The analysis of transnational migrants public action in the Rhineland Valley suggests a triple hypothesis: those transnational migrants activists elaborate a public discourse against a specific political and social stigmatization (Becker  1997); they also institutionalize and reinforce social movements with highly trained lawyers that defend their interests at the highest European jurisdictional level; they create empirically an original form of transnational quasi-trade unions.