In border region studies, the concept of (un)familiarity is applied in empirical studies of consumer culture across borders, illustrating how feelings of unfamiliarity can have an off-putting influence on cross-border interaction (e.g. because of dislike of or lack of attraction to the other side) at the same time as it can be an incentive for people living at borders to cross them (e.g. to explore the exotic other side). The concepts explanatory scope has, thus, far responded to the normative claim that a borderless Europe encourages and increases mobility. However, in previous studies applying the concept of (un)familiarity, an explanatory problem remains concerning people's unarticulated and perhaps deeper reasons for mobility and lack thereof. This leaves a question mark as to why feelings of (un)familiarity occur in the first place as well as the actual degree to which they constitute barriers and provide incentives for mobility. The concern in this article is to deepen our understanding of the concept of (un)familiarity. It enriches the bandwidth of the unfamiliarity concept by relating it to a notion of socio-spatial identity-formation, which takes into consideration the psychological aspects involved when identities form. By doing so, the concepts explanatory scope is extended, making it possible to explain some of the complexity involved when feelings of (un)familiarity occur. It, thus, also answers the question why (un)familiarity cannot be translated into normative claims about cross border mobility.