A lack of collective efficacy in neighborhoods is associated with social and physical disorder and related anti-social actions. It is less clear, however, whether collective efficacy in neighborhoods also enhances prosocial, other-regarding behavior. We studied this association by employing the Lost Letter Technique in a large-scale field experiment. Our data stem from 1,240 letters dropped in a representative sample of 110 Dutch neighborhoods, combined with neighborhood data based on a survey of residents (SSND2, n = 996) and information provided by Statistics Netherlands. We distinguish between two conditions: (1) location of the lost letter, that is, behind a car’s windshield wiper or on the sidewalk; and (2) type of addressee, that is, a Dutch name or a Turkish/Moroccan name. When we decompose collective efficacy into social cohesion and shared expectations of social control, we find that shared control expectations clearly matter for the rate of posted letters. Social cohesion has no effect. Furthermore, a high percentage of non-Western residents, high residential mobility, and a relatively low local income level are negatively related to the rate of posted letters.