This paper presents a comparative study of the development of national and regional identities in three different border regions of France: the Basses-Alpes, the Moselle and French Flanders. It demonstrates that in spite of political, economic and social differences between the regions, the presence of the border and interaction with foreigners in specifically border regions similarly influenced identity formation in interwar France. In each case hierarchies or degrees of foreignness were developed, and a specific form of national identity came to be dominant which was determined more by a differentiation from ‘others’ than through an identification with shared, centre-generated national images.