The present report is the result of a research on Positive Youth Development (PYD) conducted as a part of the national survey Health Behaviour in School-aged Children, extended to Portuguese University Youths (Jovens Universitários Portugueses) - HBSC/JUnP, aiming to address health behaviours in young people. More specifically, it focuses on the validation of an instrument aiming to assess the concept of Positive Youth Development (PYD), as a result of Portugal¿s partnership with The Positive Youth Development cross-national project, which involves more than twenty countries across Europe, Africa, Asia, the US and Latin America. The project partners are from various educational and research institutions and have expertise that is diverse and multidisciplinary, comprising health psychology, developmental psychology, social psychology, cross-cultural psychology, public health, environmental science, sociology, health promotion, speech therapy, and family studies. The PYD approach has highlighted the importance of strengthening internal and external developmental assets comprised within the social ecology of an adolescent¿s networks and opportunities.