Criminologists have documented the roles of deteriorated urban neighborhoods as areas of high crime and delinquency, but less is known about how they become high-crime areas. In this study, cross-sectional and time-analyses revealed that neighborhood deterioration precedes rising crime early in the cycle. As neighborhoods move into the later enduring stage, rising crime rates precede further deterioration. Among the changes signaling neighborhood deterioration and rising crime are a shift from single to multiple family dwellings and rises in shift from single to multiple family dwellings and rises in residential mobility, unreleated individuals and broken families, the ratio of children to adults, minority group population, females in the labor force, and nonwhite and Spanish surname population with advanced education. Early in the cycle, the speed of change in neighborhood characteristics exceeds the rate of increase in crime, while later the accelerating crime rise outstrips the velocity of change. In discussing implications of these findings for policy, the paper suggests that efforts to prevent the development of new high-crime areas focus on neighborhoods in the emerging stage of the cycle. Tables and 12 references. (Author abstract modified)