The purpose and goal of serving a prison sentence should be rehabilitation and resocialization of perpetrators so that their behaviour and life, after serving the sentence, is in accordance with the law and social norms of the society. Preparations for the release and social reintegration of prisoners should begin with the start of their prison sentence, through their inclusion in rehabilitation programs aimed at changing the perpetrator's personality. Unfortunately, personal change alone is often not enough to prevent recidivism. Over the last ten years, the focus of criminological research has changed and researchers now are focusing on the factors that deter a person from committing crimes, which is why the topic of post-penal protection and care is gaining importance. Regarding the topic of post-penal care, in the Republic of Croatia, the probation service has a significant role, because it deals in organization and provision of assistance and supervision to persons in the post-penal period. It is necessary to develop and encourage quality cooperation of all relevant institutions, services, (non) governmental organizations and local communities in order to reduce the negative effects of imprisonment and increase the likelihood of successful and complete social reintegration of persons after leaving prison. The aim of this paper is to raise awareness of the importance of organizing programs and services of assistance and protection of persons in the post-penal period in order to make social reintegration as successful as possible.