In this commentary piece, I combine insights gained from the various contributions to this special issue with my own research and understanding to trace the (dis)connections between, on the one hand, (post-)nationalism and its underlying concept of belonging and, on the other hand, cosmopolitanism and its underlying concept of becoming. I pay special attention to the human (im)mobilities mediating these processes. This critical thinking exercise confirms that the relationship between place, collective identity and socio-cultural processes of identification is a contested aspect of social theory. In the discussion, I suggest four points to be addressed in the future if we want to make existing theories about post-national formations and processes of cosmopolitanization more robust against the huge and complex challenges humankind is facing.