More than 40% of the world population is 24 years old or younger, the vast majority of whom live in low- and lower middle–income countries. Globally, a quarter of disability-adjusted life years (DALYs) for mental disorders and substance abuse is borne by this age group and about 75% of mental disorders diagnosed in adulthood have their onset before the age of 24 years . Most children and young people in developing countries, however, do not have access to mental health care.