Chicago is presented as an example of modern ghetto formation because of the great differences in crime rates among different neighborhoods. A recent study of the city of Sheffield, England, showed similar concentrations of high crime as opposed to more peaceful neighborhoods. In both the United States and England, housing markets and the allocation of public housing have contributed significantly to ghetto formation by creating the geographic and social preconditions. However, a ghetto is not only characterized by high crime rates but also by the low morale of its frequently minority inhabitants, and their isolation from other neighborhoods. Gradually, marginalization becomes a way of everyday life. Although such a division of cities into safe and unsafe neighborhoods has at times been advocated as a crime prevention measure, it is argued that this strategy is fragile and doomed to failure. Unfortunately, most western European countries have urban concentrations of minority groups who can easily become geographically isolated in a ghetto; furthermore, the break- up of eastern Europe and the creation of a border-free Europe are likely to increase the problem. Especially, in richer European countries, immigrants from economically disadvantaged areas may easily fall prey to ghettoization. 14 refs.