"Second, at the community level, disorder and crime are usually inextricably linked, in a kind of developmental sequence.
Social psychologists and police officers tend to agree that if a window in a building is broken and is left unrepaired, all the rest of the windows will soon be broken.
This is as true in nice neighborhoods as in rundown ones.
Window-breaking does not necessarily occur on a large scale because some areas are inhabited by determined window-breakers whereas others are populated by window-lovers; rather, one unrepaired broken window is a signal that no one cares, and so breaking more windows costs nothing.