The investigation focuses on 10 census tract clusters with the highest crime densities in Los Angeles County in 1970. Retrospectively examined were their crime measures and their land use, demographic, socioeconomic, and subcultural characteristics in 1950, 1960, 1970, 1973, and 1976. The general proposition derived from the findings is that the rate of change in socioeconomic status (SES) early in the development of high-crime areas exercises an extraordinary effect on the change velocity in crime; however, it is the rate of change in the crime measure that takes over in the course of time to 'derive' change rates in the SES component of neighborhood social structure. Since a high degree of collinearity exists among all structural components, it follows that the velocity of change in crime ultimately becomes the main determinant of the pace at which change occurs in the social structure of high crime areas. A policy implication is that intervention in newly emerging crime areas may prevent them from becoming irreversibly lost to crime. Intervention might include vigorous local political control of zoning, planning, and building code requirements so that the proportion of lower class residents is kept to a minimum. Further, social and educational services should help lower class families cope with their economic and social problems and adapt to general neighborhood norms. The appendixes detail some of the findings and methodology, and a bibliography contains about 60 listings.