In Europe, the most significant contribution to epidemiological research has been given by the operation of the European Monitoring Centre for Drug and Drug Addiction (EMCDDA). The EMCDDA has developed, in close cooperation with the Reitox network, five key epidemiological indicators to provide reliable and comparable information on drugs and drug addiction in Europe. In parallel, other projects related to the monitoring of the phenomenon of addiction were carried out independently. Important examples are the ESPAD study and the HBSC study. The research, by providing information on health needs, allows to plan social and health policies, to implement prevention programs and evidence-based care interventions.