These changes taking place in community life may be observed in a dramatic form in commercialized recreation. The day of the neighborhood public dance hall and the neighborhood motion picture show has passed, or at least is passing. Young people are deserting the neighborhood recreation centers and are thronging to centers outside the local community, to the high-class, magnificent dance gardens and palaces, and to the so-called “wonder” theaters of the “bright light” areas. A realignment of the leisure-time movements of urban young people is taking place, which every agency engaged in neighborhood work must take into account. Is the neighborhood as a factor in the lives of youth soon to become a situation of the past? Can settlements and social centers expect to hold back the tide of the forces of city life? A map of the residences of dance hall patrons which shows both the disappearance of the small public dance hall from the neighborhood and the concentration of large dance halls in “bright light” areas is all the more significant because it portrays the phenomenon of promiscuity. By promiscuity is meant primary and intimate behavior upon the basis of secondary contacts. In the village type of neighborhood, where everyone knows everyone else, the social relationships of the young people were safeguarded by the primary controls of group opinion. But in the public dance hall, where young people are drawn from all parts of the city, this old primary control breaks down. Is not this the basic reason why social workers find the dance hall so recurring a factor in personal disorganization and delinquency? As yet, however, we have no satisfactory study of the dance hall as a social world of youth. Two new social types—the “sheik” and the “flapper”—have been created by the dance hall and the motion picture, but they are regarded as subjects for jest rather than for serious study. [Illustration: FORM 1.—The Neighborhood Triangle. ] A study by Miss Evelyn Buchan of girl delinquency shows the effect of the increasing mobility and promiscuity of city life upon the behavior of youth, and suggests an interesting method of study. To bring into clearer relief the rôle of mobility and promiscuity as factors in behavior, a device called “the delinquency triangle” was employed. The three points of the triangle were located by spotting the home of the girl, the home of her male companion, and the place of delinquency. Three typical forms of the triangle soon appeared. Form 1 represents the traditional form of sex delinquency, where all three points of the triangle are within the community. This may be called the “neighborhood triangle.” In this case the intimacy of the boy and girl might be little more than the continuance in this country of old-world folkways, but without the protection for the girl in subsequent marriage which the European peasant mores afford. [Illustration: FORM 2.—The Mobility Triangle. ]