It is argued that the geographic concentration of the poor often serves to concentrate other negative social and physical conditions. From this ecological perspective, the growth of concentrated poverty is examined in Cleveland (Ohio). The investigation uses a database developed for Cleveland and its suburbs with information on social, economic, demographic, and physical characteristics, as well as the incidence of selected social problems. The area covered by poverty conditions in Cleveland has grown geometrically since 1970. Poor areas now cover more than one-third of the city. Six indicators of the well being of children demonstrate that children in the high-poverty areas are at greater risk than those in the low-poverty areas, even though the impact of the concentration of poverty is not uniform for all indicators and is mediated by other factors. Demographic factors are interrelated with social conditions as well. Knowledge of what accounts for the differential effects of poor neighborhoods on children can lead to preventive interventions at the neighborhood level. Five tables present study findings. (Contains 25 references.) (SLD)