Which QS have been implemented in the EU?; 2. Which are examples of inspiring practices of the implementation of QS?;3. What generic recommendations can be formulated for successful QS implementation?1 | This project was drafted before the present European Drug Strategy 2021-2025 (Council of the European Union, 2020) was adopted, and therefore DDR activities refer not only to prevention, treatment, and social reintegration, but also to the harm reduction field.