This study examines whether the values prevalent in one's social environment moderate the link between immigration-related ethnic diversity and social trust. Drawing on arguments related to intergroup relations and anomie, we expect that contexts characterized by a comparatively high degree of openness mitigate a trust-eroding effect of immigration. In contrast, we expect that contexts of low openness or high conservation may reinforce a trust-eroding effect. We test these propositions using survey data from Europe and the United States merged with regional indicators on immigration and value contexts. The results show that high levels of contextual openness attenuate trust-eroding consequences of immigration growth. With regard to mechanisms, we find that contextual openness moderates how change in immigration relates to generalized forms of trust rather than outgroup trust. This points to an overall anomie-reducing function of openness norms, especially in times of ethnic change.