This project aims at developing best practice guidelines for the detection, prevention and treatment of substance abuse in children and youngsters age 12 to 18, using the ADAPTE process. The prevalence of problematic alcohol and drug use in the Belgian population of children and youngsters will be calculated. In addition, an overview will be presented of organisations, target groups and stakeholders involved in drug- and alcohol prevention and treatment in Belgium. The phase of adaptation will be the main focus of the research project. The project will result in (a set of) context-specific, best practice guidelines on the detection, prevention and treatment of alcohol and drug abuse in children and youngsters, adapted from existing, international guideline