The group has evolved to include the victims and perpetrators of bullying, isolated pupils, those with poor peer relationships or who have poor social skills, the emotionally stressed and those with backgrounds deficient in love and care.
The idea came from school nurse Anne Arbuthnot's confidential drop-in clinic, held twice weekly, in which she raised concerns about risk-taking behaviour that she felt was based on low self-esteem.
With the principal teacher of pupil support, Eleanor Simpson, she devised a programme of 10 80-minute sessions held weekly to support vulnerable girls.
"Eighty per cent are referred by pastoral staff or through the drop-in clinic, but it remains entirely voluntary - it wouldn't work if it wasn't," says Mrs Simpson.
"Importantly, pupils are withdrawn from mainstream classes during school hours to take part, but we hold the sessions in a local youth centre and not on school premises."
The group work includes discussion and role-play, aerobics and creative activities, manicures, hand massage and aromatherapy as well as healthy snacks.
"We stress the social side to attract them, explain what self-esteem is and why they have been referred," says Mrs Arbuthnot.
"We reassure them that it's not a 'bad girls' group - there is no stigma in the school attached to those who come - and together we set the rules on confidentiality, disclosure and behaviour, drawing up a contract that is signed by them and us and by their parents. In everything we do, we look at self-esteem as it affects all the senses - hence the hand massage, aromatherapy and healthy food.
"We find that the girls provide each other with a lot of positive support.
They learn that it's about serving and receiving as well as about self-support."
But the sessions are not programme-led. Targets are set by the pupils themselves - giving up smoking or losing weight, for example.
"The hope is that the group will give them a strength they can rely on and learn from, an experience to remember," says Mrs Simpson. "At the end, there's a shared expectation of positive behaviour and attitude."
The groups can be diverse, although too diverse an age range does not work.
"It's working together that's effective," adds Mrs Simpson. "The girls discuss their own skills and strengths. You often find that the quiet pupil can make the dominant pupil calmer, and the more outgoing pupil can bring out the quiet one, but the group must always be led."
The girls' group has now been running for five years, with two 10-week courses run every year. So far, only one group has had to be abandoned because the bonding proved to be ineffective.
The participants sometimes refer themselves and later recommend the group to friends. That, says Mrs Arbuthnot, is "the best recommendation".
Kate, now an S6 pupil, says: "I went for 10 weeks in S4. I find it easier to meet new people now. It helped my confidence. I've always wanted to be a counsellor, and it reinforced in me that that's what I want to do."
Gemma, in S2, agrees. "I went last year for eight weeks. It helps with your confidence and has improved my behaviour," she says.
The group has also helped Grace, an S4 pupil, to get through a tough transition in her education.
"I had just moved from another school," she says. "It helped my confidence and helped me to make new friends. I really enjoyed it."
At the end of 10 weeks, the group usually visits Edinburgh's Megabowl, an added attraction for many youngsters.
The participants give their written feedback alongside evaluations from senior management and pastoral staff.
Outcomes to date include:
* enhanced knowledge on personal safety issues
* increased range of friendships
* better communication skills , assertiveness, problem-solving and decision-making
* improved confidence and ability to cope with home and school pressures
* reduction in bullying; and
* reduction in self-harm