The project is focused on the lack of interventions in the European prisons for drug-dependent persons and the absence of programs according to the inmates’ and ex-inmates needs. The main objectives are the assessment of the inmates and ex-inmates on drug and alcohol use and, based on the results of this assessment, the design of appropriate interventions for the specific target groups with the aim to implement and evaluate them in a second call in the future. The expected impact from the implementation of this project is the reduction of drug use in prisons, the mapping of the drug use in prisons and the design of interventions based on the inmates’ and ex-inmates needs. More specifically, the interventions will be based on treatment and harm reduction as well as proposals for the social reintegration of ex-inmates. The outputs of the action are to assess the needs of inmates with the use of existing instruments with a sample of 400 inmates and 50 ex-inmates approximately in each country. The implementation of the instruments will allow the participating countries to keep a personal record for each inmate and provide data to the EU when necessary. Also, to evaluate the existing programs implemented in the prisons with the intention to propose appropriate interventions according to their demands. Additionally, a manual with best practices will be written based on the experiences and knowledge gained from the action. The outcomes of the action is the improvement of the existing instruments according to each country’s needs; the design of interventions for all target groups; the cooperation with other European countries for the implementation of best practices in the prison system and the dissemination of the outcomes with the publication of a manual as well as articles in scientific journals and presentations in Conferences.