GreenComp in Action aims to strengthen the quality and relevance of youth work by equipping youth workers with practical competences to integrate sustainability into non-formal education in a structured and inclusive way. By implementing a seven-day mobility in Thessaloniki for 24 youth workers from Greece, Latvia, Portugal and Türkiye, the project will move sustainability from a general theme to a competence-based learning approach that youth workers can apply in their everyday practice with young people. The project objectives from the perspective of youth work practice are to enable participants to use GreenComp as a planning and reflection tool when designing youth work activities, so that learning goals are clear, coherent and measurable. It will strengthen participants’ facilitation skills and methodological toolbox by providing and testing non-formal education methods that engage young people actively, encourage critical thinking, and support inclusive participation, including when economic and geographical barriers shape young people’s opportunities. It will also improve youth workers’ capacity for simple project planning linked to sustainability learning, helping them connect workshops with realistic, low-effort follow-up actions that fit normal youth work routines. Through peer learning and intercultural cooperation, participants will exchange approaches, adapt methods to different contexts and build confidence to deliver sustainability workshops that are feasible, youth-friendly and impactful. At organisational level, the project will support partner organisations to enhance quality and innovation by embedding competence-based sustainability learning into their regular programmes, supported by internal sharing moments and accessible materials. Overall, GreenComp in Action will professionalise how youth work contributes to the green transition by strengthening youth workers’ competences, improving learning design and delivery, and making sustainability education more inclusive and transferable across diverse youth work settings.