YOUNGMOB is addressed to deliver practical tools for parents and school teachers to promote a correct use of smartphones and avoid or reduce addictive behaviours; and a set of recommendations also for policy makers to prevent mobile addiction. For doing that, YOUNGMOB will develop two IOs: (i) an innovative toolkit with an app that allows parents and teachers to tutor that accompany the youngsters in the process of learning a correct use of smartphones with useful and practical materials to schools and parents to design tailor-made strategies to promote a correct use of smartphones in youngsters; and (ii) a White Paper to promote the correct use of mobile phones among youngsters and prevent the mobile addiction for parents, teachers, educational professionals and policy makers. The project will involve experts in the field to validate the project outputs (12 in total) and the active participations of schools, children and parents in Spain, Italy, Slovenia and Portugal. Participants will test the app, co-design the materials, define their needs through focus groups and interviews, etc. At the end of the project, 4 multiplier events will be developed to disseminate the project outputs and guarantee their sustainability.