The use of psychoactive substances (PAS) has particularly harmful effects among adolescents and young adults. Such use remains high in Europe—particularly in France—and in Anglo-Saxon countries, though a downward trend is beginning to emerge. It is important to monitor these developments and attempt to explain them. Drawing on the literature and data from recent surveys conducted by the French Monitoring Center for Drugs and Drug Addiction and by Santé publique France, this report provides a non-exhaustive overview of trends and patterns of PAS use among young people in France and abroad, and offers possible explanations for the observed trends.