The findings indicate that, while some changes in the long-term subgroup parallel those in the overall prison population, other changes are distinctive to that group. While the most obvious change in the New York prison population is its dramatic increase in scale, the findings also reveal that the characteristics of the prison population are also changing. The increasing proportion of robbery, homicide, and drug offenders has displaced many less serious offenders. The number of prisoners with histories of drug use and prior criminality have increased, and the racial composition of the prison population has changed. The long-term and very long-term subpopulations have become more homogenous in terms of seriousness of offense and prior criminal record, presenting severe management problems to corrections officials. The social characteristics of these two groups have also changed to a much greater extent than in the general prison population: long-term offenders are more likely to be black or Hispanic, young, pre-prison drug users, and homicide offenders. This sort of trend analysis can be useful in planning new prison facilities and designing programming. More research is needed on the prison response of these time-served groups. 8 figures, 4 notes, and 20 references