The need to focus on the mental health of adolescents is gaining increasing recognition as the global community looks to achieve the Sustainable Development Goals (SDGs), in particular SDG 3: “Ensure healthy lives and promote well-being for all at all ages” and SDG 10: “Reduce inequalities within and among countries”. With adolescents comprising 16% of the global population, it is vital to address the main threats to their health in order to achieve the SDG targets. Mental health conditions account for a considerable proportion of the global disease burden during adolescence and are the leading cause of disability in young people. Up to half of all mental health conditions start before the age of 14 years. Suicide is one of the three leading causes of death among older adolescents. Poor mental health in adolescence portends a range of high-risk behaviours, including self-harm, tobacco, alcohol and other substance use, risky sexual behaviours and exposure to violence, the effects of which persist and have serious implications throughout the life-course. There are multiple opportunities for health promotion and disease prevention in adolescence, which could benefit young lives in the short and long term. This stage is deemed as one of the optimal timeframes for intervention, given the neuroplasticity evident in adolescence and the opportunity to step in at a time when the majority of mental health conditions and risky behaviours have their onset.