This is one of the most famous works of Robert Park - Chicago School theorist and one of the founders of the urban sociology which is for the first time published in Russian. The city is convenient for the Park "locus of research", since it is here that any feature of human behavior concentrated on a relatively small (foreseeable) space, the natural growth of the institutions is the fastest. In the published article, despite the fact that it may seem a review, recorded a number of basic methodological positions - both in terms of the city, the dynamics of its social development and differentiation, and relative to the social sciences have reached a point where it became possible to organize and carry out laboratory experiment.