The existing literature on diversity and trust has focused on a unidimensional understanding of diversity. We argue that a unidimensional approach is theoretically and empirically problematic and use a recently developed multidimensional measure of social structure to investigate which aspects of diversity are associated with generalized trust. We run cross-country regressions with up to 115 countries to explore the importance of fractionalization for average trust levels 1981–2008. Using several different measures of ethnic fractionalization, we do not find a general and robust relationship between ethnic fractionalization and trust. In line with expectations, however, we find a negative and significant association between ethnic fractionalization and trust for low levels of ethno-religious cross-cuttingness and cross-fractionalization, illustrating the importance of multidimensionality.