The organization of the English penal system gives wide- ranging discretionary powers to individual governors, so that particular rehabilitation programs may exist at one facility but not at others. Models of penal reform discussed here include the rehabilitation model, treatment model, justice model, rehabilitation as reinstatement, cognitive-behavioral model, and selective incapacitation. The three main problems faced by prison libraries in meeting their role as an effective agent of rehabilitation include inadequate resourcing, inappropriate staffing arrangements, and a sense of being regarded as a peripheral resource by other prison departments. Despite these obstacles, prison libraries can influence many factors significant to the rehabilitative process by providing information, helping inmates develop practical skills, supporting prison education, developing inmates' self-motivation, offering inmates a chance to use their time constructively, counteracting negative aspects of incarceration, providing inmates with insight, providing a calming influence for inmates, and altering inmates' moral behavior. 1 table, 1 note, and 79 references