Three in four young people with mental health problems are not receiving the treatment they need, according to a report by New Philanthropy Capital.
The charity estimates that£244m to£376m could be saved each year by ensuring services were provided to all young people with conduct disorder.
The report, called Heads Up, says charities play an important role in providing support, carrying out research and campaigning to change policy and perception.
Chief executive Martin Brookes said: "Helping children at an earlier stage stops troubled kids from becoming troubled adults.
"It can save individuals and families years of distress, and the state millions of pounds.
"Charities support young people suffering from problems such as depression, eating disorders and self-harm who would otherwise be left out in the cold."
The report looks at the charity the Place2Be, which provides counselling in 146 schools.
Chief executive Benita Refson said charities' role needed to be recognised: "People are beginning to realise that mental health issues lie behind many of society's problems, but charities need increased support and recognition to meet rising demand."