Purpose: Declining mental health has been observed in young people from across the globe since approximately 2010. One contributing factor may be the erosion of meaningful and supportive social connections. Fostering positive social connections and a focus on the social networks of young people could be a key strategy to enhance youth mental health and wellbeing. It is now well established that positive social connections benefit mental health. Social connections to peers and school communities become increasingly important during adolescence, a unique developmental window for prevention and a time in which peer influence increases. Key findings: While our understanding of the importance and utility of adolescent social connection to improve mental health is evolving, social network approaches and strengthening connections at school hold promise to improve youth mental health. We outline key evidence across two domains of social connection; the importance of peer connections and school connectedness. We also explore the application of Social Network Interventions (SNIs) as an emerging way to promote positive mental health and decrease key risk factors for poor mental health across youth social networks. Conclusion: Prevention strategies could target youth social connection as a transdiagnostic factor to improve youth mental health. This may take the form of interventions that leverage the importance of peers, create supportive social networks and environments, as well as the use of social network frameworks to develop an understanding of the mechanisms by which preventive interventions spread throughout different social networks.