At the Federal Correctional Institution (FCI) at Tallahassee, Fla., the daily number of inmates in residence was recorded for 36 months, the number of square feet of living space available to the inmate population per month was determined. Density was calculated by dividing the number of square feet by the monthly population, and incident reports charging inmates with disciplinary violations were recorded. Population size was significantly correlated wiih the number but not the rate of disciplinary violations. The total amount of personal space and the index of population density were significantly correlated with both the number and rate of violations. A post hoc analysis showed that the incidence of uncomfortable hot days had a relation to disruptive behavior. These results were contrasted with laboratory data on human crowding reporting no relation between population density and behavior pathology. Perhaps the chronic high density explored in this study differs from temporarily crowded conditions produced in laboratory research on human crowding. Chronic high-density living conditions were associated with negative behavior when crowding was involuntary and when there was little hope for relief. A table and 31 references are provided. (Author abstract modified)