The ecological structure of Racine, Wis., was examined for 1950, 1960, and 1970 (and to a limited extent for 1980) from block data aggregated into various statistical units, census tracts, police grid areas, natural areas, and neighborhoods. Patterns of crime and delinquency were measured by official police data for 1949-79 for the entire city and for three cohorts of persons born in 1942, 1949, and 1955. The cohorts consisted of 6,127 male and female juveniles whose police contacts, court dispositions, and places of residence were traced from 1950 through 1976. The cohort data were used to determine whether there was spatial variation in delinquency from cohort to cohort and within cohorts over time that followed the general pattern of spatial variation with other data sets. The study found that although the ecological characteristics of neighborhoods significantly affected crime rates, the effects were not constant over time. Police and court response to offenders from inner city areas tended to be more intense and severe than for offenders from other areas. The police and courts also tended to focus on juveniles. The study concludes that money would be better spent in revitalizing inner city and transitional areas rather than in formally processing and incarcerating youthful offenders. Graphic data.