An analysis of the studies revealed that they suffered from considerable methodological problems, including the use of inadequate research design and unsystematic sampling procedures. The types of subjects and time periods used varied widely, thus making a comparison of the findings, at times, difficult. The results however, suggested that imprisonment is not harmful to all individuals. Some persons deteriorated in response to confinement, other persons improved their functioning, and still others showed no appreciable change. A complex interaction of factors including individual difference variables, institutional orientation, degree of crowding, phase of sentence, and peer group affiliation seems to influence an individual's response to confinement. The findings also have implications for current correctional controversies such as the 'nothing works' issue and the relative value of determinate versus indeterminate sentencing procedures. Future research should further clarify the effects on prisoner adjustment of intrainstitutional variables such as crowding, solitary confinement, prison policy changes, and peer group affiliation. The various patterns of adaptation to confinement in relation to individual difference variables also should be explored. Over 135 references are appended. (Author abstract modified)