Introduction to the special issue "Youth and Addiction: Changing Behaviors and Professional Practices," coordinated by Emmanuelle Bauchet, a public health physician and head of the Lifestyle Division within the Programs Department at INPES, François Beck, statistician and sociologist, director of the OFDT, researcher at Cermes 3, Jean-Pierre Couteron, clinical psychologist, Youth Consumer Consultation (CJC) at Le Trait d’Union (Boulogne-Billancourt), president of the Fédération Addiction.