We explore how the quality of friendships in adolescence, defined by features such as trust, intimacy, conflict resolution, companionship and emotional support, relates to adolescents’ subjective wellbeing, mental health and social developmental trajectories. By bringing social network awareness and rigorous measurement into the study of friendship quality, our work aims to inform interventions that are not just about “peer influence” or “peer groups” but about deeper relational quality and its implications for adolescent health.