Teachers across Scotland credit the xlerate with xl programme, run by the Prince's Trust Scotland, with turning round youngsters who were heading for trouble.
And many will be very concerned at the funding threat now facing the programme under a new concordat between local and national government.
It means that the Youth Crime Prevention Fund - a major source of money - will cease to exist in April. In addition, the removal of ring-fencing from the Determined to Succeed programme means that funding from that source is also no longer guaranteed.
Paul Watson, winner of the "Glasgow young person of the year award" while a pupil at St Paul's High in Glasgow, is just one of the xlerate programme's success stories.
He was "a nightmare", said teacher Ronnie Martin, until he joined xl. Now Paul works for the Royal Bank of Scotland.
Thirty S3 and S4 pupils take part in the xl club at St Paul's High, run by Mr Martin, an English teacher, and a community education worker.
The club, said Mr Martin, is not for "bad kids". "It's for kids who lack confidence or who are truanting more and more because they have become disengaged," he explained.
But the xlerate programme allows them to experience success through many activities. It shows pupils what their strengths are.
"If we lost xl we could not replace it," said Mr Martin. "The scheme has created some very, very successful young people whose performance in S1 and S2 did not indicate that was the way things would turn out. Something like this is essential, especially for a school in Pollok. If we don't have programmes that help these pupils, then they are in danger of falling off the edge of the world."
There are 126 secondary schools across 31 of Scotland's 32 local authorities which use the xlerate programme to reach some 2,500 pupils.
Xl clubs usually replace one subject on the timetable of youngsters aged 14 to 16 who are disengaged and underachieving.
According to the Prince's Trust Scotland: "Xlerate with xl encourages young people in Scotland to make the most of their time at school, boosting their motivation and developing their enterprising and working skills for later on in life."
An evaluation of xlerate with xl, published in 2006 by Durham University, said it was "an excellent and very effective programme" which has had "a significant impact" on young people.
Until now, the Prince's Trust Scotland has been able to claim that 89 pence in every pound of all the money it receives goes directly to helping youngsters.
Now it fears that the new funding arrangements negotiated by the Scottish Government and local authorities will not only increase the charity's administrative burden, but also mean that some authorities may not choose to fund it. Instead of negotiating centrally, it will have to reach an agreement with each individual authority.
Finlay Laverty, head of commercial development at the Prince's Trust Scotland, believes that the large charities that operate across Scotland will need two to three years to "build relationships with local authorities" and "make the transition".
The trust's "Team" initiative, a 12-week course run in colleges that aims to help vulnerable young people get their lives back on track - those leaving care and prison, for instance - is also under threat, says the Prince's Trust Scotland.