This paper presents the possibilities of adult education in the prison system in different countries in the world and in the Republic of Croatia. In the paper, the author describes prison systems in which prison treatment is based on work obligations and educational programs, their development throughout history and the purpose of execution, as well as the role of education in prisons which varied both historically and territorially. The roles of teachers and students in educational process are also described, as well as the importance of self-initiative involvement of prisoners, which should be marked by a high level of motivation, and the implementation of the educational process in its conditions of imprisonment, exceptional control of students and specific rules of conduct present in the penitentiary institution. The contribution of education in the resocialization and reintegration of convicts and in the reduction of recidivism is emphasized. As part of the study of the above, one enters the field of andragogy and the penology field. Given that education in prison systems is one of the forms of adult education, the paper emphasizes the importance of adult education, which is based on the principles of lifelong learning to which every person is entitled in all circumstances and which helps to achieve greater competitiveness in the labour market, and permanent employability.