Borders and bordering are inevitably implicated in the migration phenomenon, from the perspective of both migrants and the receiving societies. We will highlight some of the ways in which borders are set and practiced. Specifically, we will argue that negative attitudes towards migrants and refugees are shaped by how people define their own identity. We will first focus on the dissolution and reconstruction of borders in the experience of migrants, then, based on a social psychology perspective, we will discuss how cognitive and symbolic borders separating immigrants from native-born people are built on the basic process of self- and other- social categorization. Finally, we will present some of the self and identity theories that make it possible to overlap and blur boundaries, hence opening routes for more positive social encounters.