Schools are missing children's mental health problems because training in this area is "non-existent", MSPs believe.
A Scottish Parliament committee inquiry into child and adolescent mental health services found these were blighted by policy-makers' complacency, leading to long waits for treatment and parts of the country where children receive irregular help.
MSPs believe early intervention is crucial to any improvement - and that teachers should play a pivotal role in that process.
In a parliamentary debate this month, Liberal Democrat Hugh O'Donnell stated that, due to lack of training and pressures such as exams, teachers were unable to see that bad behaviour might point to "something deeper". As a result, children were being excluded rather than going to the appropriate service.
Mental health problems often led to inappropriate sexual behaviour or self-harm, said Ian McKee (SNP), yet "teacher training in these matters is patchy or non-existent".
Teachers should be able to call on "clear guidance" on how to deal with precocious sexual behaviour, and a mentoring system for less-experienced teachers could help.
Both MSPs echoed comments made to the inquiry by Brian Cooklin, headteacher of Rutherglen's Stonelaw High and a former School Leaders Scotland president. He stated that teacher training did not seem to cover mental health, and that no consistent approach was taken with existing teachers.
Families often felt "abandoned" when a vulnerable young person left school, said Rhoda Grant (Labour), who backed the committee's idea of a "transitional service".
Former Education Secretary Cathy Jamieson (Labour) bemoaned the loss of a successful trial project which had seen a specialist mental health nurse working at Dalmellington's Doon Academy in her constituency.
The success of Place2Be, a charity which provided in-school counselling and contributed most of the required funding, was highlighted by Richard Simpson (Labour). Place2Be was struggling to find local authorities willing to work with it, despite success in Edinburgh.
Paul Hunter, headteacher at Edinburgh's St Catherine's Primary, told The TESS about the impact made since Place2Be arrived at the school five years ago. A counsellor spent three days a week at the school. One-to-one counselling was given to about 10 children - an hour each, once a week - for up to a year. Group work addressed issues such as confidence and transition, drop-in appointments encouraged children to raise issues as they cropped up, while playground "chat stops" involved two trained P7s listening to their peers' problems.
The big advantage was continuity, Mr Hunter explained. Issues could be dealt with immediately, rather than having to wait weeks for a response to a referral, and children gained trust because they would see the same person each time. He cited one pupil who would have been excluded, but for Place2Be. The cost of working with a child through the charity came to a five-figure sum, but it would be six figures if the child were excluded and subsequently home-schooled.
Looking at the national picture, health and sport committee convener Christine Grahame (SNP) was concerned by "some complacency" among those responsible for putting a children's mental health framework in place by 2015.
Children's mental health services were even more neglected than general mental health, surmised Michael Matheson (SNP): they were "the Cinderella of the Cinderella service, as they are often not a priority".
- More than 7,000 children in Scotland have been admitted to hospital after self-harming over the past decade, according to official figures released this week, following a parliamentary question from Liberal Democrat health spokesman Ross Finnie. Some 563 children aged under 16 were admitted to hospital for self-harming in 2008-09.