In 2004, after several years of legal and structural adjustments, the Polish-Ukranian border ceased to demarcate just a divide between two nation-states, and instead became a frontier of the transnational European community. This research is an anthropological and historical assessment of how the Polish state establishes, maintains, legitimizes and naturalizes this evolving border arrangement, and how the emerging classification of populations and territory materializes in the daily understandings of individuals and groups. Employing archival work, formal interviews and participant observation, the researcher will produce an ethnographic account of this reorganization of space and traffic, by documenting how belonging to, and exclusion from a supranational community are defined and enacted in key sites through the adjustment of legal structures and political rhetoric, narratives, official actions and informal practices of state officials as well as of persons involved in two-way cross-border traffic. The research will contribute an insight into the processes of social construction of difference that under the new border regime will concern Eastern Europeans from outside of the EU.