Adolescence is one of the most rapid and formative phases of human development. During this time adolescents develop knowledge and social-emotional skills and acquire attributes and abilities that are important for assuming adult roles and active contribution to society. Up to 50% of all mental health conditions start before the age of 14 years and up to one in five adolescents experience a mental disorder each year. Suicide is one of the three leading causes of death among older adolescents. In turn, poor adolescent mental health is associated with a range of high-risk behaviours, including self harm, tobacco, alcohol and substance use, risky sexual behaviours and exposure to violence, the effects of which persist throughout the life-course and have serious implications.