The issue of identity spatialisation lies at the interface between classic theories of social identity in social psychology and the environmental psychology approach in terms of sociospatial identity. This study of adolescents and young adults aimed to identify the influence of belonging to a place on self-construction according to place of residence in France. Two regions were compared: (a) the French Basque region, where there is high cultural specificity; and (b) Bordeaux region, which is less culture-specific. Data were collected from 229 adolescents and young adults from these two regions. The feeling of belonging to a region, sociospatial identity, and social identity were estimated using self-report questionnaires. Results demonstrate the existence of several forms of sociospatial identity. Basques tended to overinvest on the regional level—especially when they spoke the Basque language (Euskara)—whereas the sociospatial identity of Bordeaux inhabitants was multi-level. Furthermore, the expression of sociospatial identity was age-dependent. These findings help to define, measure, and interpret the processes and dynamics of identity associated with belonging to different territories.