Considering of ouspreading of criminality as inevitable social phenomenon in all, including the Croatian society, it is important to question efectiveness of prison as institution. Managing and working in the prison institutions are not same as working in the factories and offices. When it's talked about work, prisons and penitentiaries, it is though about managing of human beings, especially in situation when one group of people have significant formal power over someone else. That means that there are questions what outperform effectiviness and ability. By making decision about treatment human beings, there is basic scrupulosity, question is correctly what someone is doing. Actually, the goal of this paper is to show elements upon which the process of punishment within prisons is based, a complex process that should lead to the re-socialization of prisoners and their training for adequate functioning in the society. Because of constant increasing the number of prisoners, it comes to the problems and shortcomings that prevent the fullment of the basic functions of a prison sentence, arising from as well as leading to prison overcrowding.