Irma Clots-Figueras, Paolo Masella Cultivating and maintaining a sense of national identity is a critical challenge facing modern states. States whose citizens identify more strongly with local political units than the nation as a whole may face difficulties in solving collective-action problems, in sustaining support for social safety nets, and in preventing secessionist movements. Such movements are present in many European countries, such as Belgium, France, Italy, Spain, and the UK. Regional mixing to foster a shared identity Historically, governments have tried to strengthen a shared national identity through various measures, including national education programs, media propaganda, and resettlement schemes (Bandiera et al. 2019, Blouin and Mukand 2019, Cantoni et al. 2014, Clots-Figueras and Masella 2014). Another commonly applied tool for strengthening a shared national identity and increasing social cohesion is conscription. A key feature of conscription, as adopted by many countries, is the purposeful mixing of conscripts from different regions of origin in the same units, motivated by the belief that mixing fosters interregional relationships and identification with the nation state (Bertaud 1979, Krebs 2004). According to the contact hypothesis, mixing people from different regions can strengthen interregional sympathies, particularly when the contact involves equal status between groups, common goals, and cooperation (Allport et al. 1954, Lowe 2020). A number of studies also suggest that contact helps to decrease prejudice and correct biased beliefs (Burns et al. 2018, Paluck et al. 2019, Pettigrew and Tropp 2006, Schindler and Westcott 2020). The overall impact of contact on shared national identity is less clear. By increasing sympathy and reducing intergroup biases, interregional contact may help to increase the extent to which individuals from different regions share a common identity. However, differences between one’s own identity and others’ identities might also become more salient in response to contact with dissimilar people, thereby decreasing a sense of shared identity (Tajfel et al. 1979).