The World Health Organization estimates that one in four people will suffer from some form of mental disorder in their lifetime.
It is something that affects people of all ages, including up to 20 percent of children and teenagers.
Figures show that every year, one million suicides around the world are related to mental illness - or one suicide every 40 seconds.
But the good news is that mental illness can be treated successfully.
On this edition of Inside Story, we ask if enough is being done to help those in need, and if taboos and discrimination surrounding the illness still exist.
Presenter: Shihab Rattansi
Dr Ziad Kronfol, a professor of psychiatry at Weill Cornell Medical College, Doha
Dr Suhaila Ghuloum, the head of the psychiatry department at Hamad Medical Corporation, Doha