As a sociologist, I am interested in context effects for individual behavior. Individual action is not only driven by own preferences and goals but the surrounding context also determines what people do. A perfect research site to study this claim is the residential neighborhood. Do neighborhood contexts and the composition of people, who live there, matter for the behavior of passengers? More in detail, are people more inclined to do favors for a stranger in neighborhoods, when social norms concerning collective efficacy are tight and the neighborhood is more advantaged in general? The answer is ‘yes’: in a number of field-experiments we were able to show that people behave more prosocial in neighborhoods with high collective efficacy, i.e. the shared norm that everyone will intervene on behalf of common goods.