Social and behavioral scientists have long investigated the relationship between interpersonal trust and features of the environment. However, it remains unclear how the microenvironment of relational distance (i.e., social proximity between 2 persons) interacts with the macroenvironment of human ecology (i.e., social and natural environments) to predict people's levels of trusting other persons. In this research, we tackled this puzzle using diverse methodologies (e.g., meta-analysis, experiment, and multilevel analysis) and large, cultural-group samples. Four studies found that, across many countries (e.g., 77 countries in Study 3) and regions within a country (e.g., 28 Chinese provinces in Study 4), members of these social units trusted close others (e.g., family members) more than distant others (e.g., strangers). However, this general effect of relational distance was stronger in societies embedded within more restrictive cultural, sociopolitical, and natural ecologies (e.g., a more collectivistic cultural logic, less developed socioeconomic and political institutions, and a stronger threat of infectious diseases, such as HCV infection). More importantly, people's attitudinal trust of distant others was higher in countries or regions with less restrictive ecocultural features, but such differences often disappeared in the context of trusting close others. Compared with other sociopolitical and natural features, the societal culture of collectivism often was a unique explanatory variable for the micro-macro interplay of current interest. These converging pieces of evidence provide a clear view of how levels of interpersonal trust vary as a function of relational distance and ecocultural environments simultaneously.