Abstract : Two major surveys, conducted every 4 years for the past 25 years in the adolescent population, allow for an international comparison of drug use: the Health Behaviour in School-Aged Children (HBSC) survey, under the auspices of the World Health Organisation (WHO), and the European School Survey Project on Alcohol and other Drugs (ESPAD), conducted with the support of the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) and CNR Institute of Clinical Physiology (IFC). This issue of Tendances looks back at the main findings of these two surveys, with updated reports published in 2020. With a strong emphasis on mapping and infographics (some sources are available in the appendix), it offers an overview of European developments in adolescents' initiation into and consumption of tobacco, alcohol and cannabis between the ages of 13 and 16 (including a box on other illicit drugs and the use of electronic cigarettes in 2019), over almost a quarter of a century.