Empirical research suggests that societies that are diverse as a result of international migration have lower levels of social trust, but little is known about the mechanisms underlying this relationship. The authors test one possible mechanism: that conationality increases interpersonal trust and the willingness to reciprocate trust. As part of large-scale surveys in the United States, South Africa, and Switzerland, respondents were presented with trust vignettes in which information about the nationality of the interaction partner was systematically varied. Despite overall country-level differences in levels of trust and trustworthiness, no in-group bias associated with conationality was found in these types of interactions. This suggests that the negative association between ethnic diversity and social trust cannot be explained by differences in relational trust conditional on sharing the same nationality.
