A study on violence in urban neighborhoods in the mid-'90s showed that lower rates of violence occur in neighborhoods characterized by "collective efficacy" - that is, mutual trust among residents and a willingness to intervene in the supervision of children and the maintenance of public order. Members of a successful neighborhood feel connected; what is key, as stated in an article on the study in Science magazine, is a "willingness to intervene on behalf of the common good."
The study was conducted by the Project on Human Development in Chicago Neighborhoods, directed by Felton Earls, MD, under the auspices of the Harvard University School of Public Health. Dr. Earls notes that "growth or maintenance of neighborhood efficacy depends upon the commitment of individuals but also external supports that enable trust and cooperation to flourish." As a New York Times article noted at the time, cutting public support for neighborhood institutions such as parks is shortsighted and can lead to increased violence.
Learn more about the Project on Human Development in Chicago Neighborhoods