Teachers are uncertain about how to deal with pupils' poor behaviour such as vandalism and verbal abuse, experts say. But they say exclusion and the growing use of anti-social behaviour orders are not the way to stop young people going on to cause trouble outside schools.
Their concerns follow an Asbo issued to a 14-year-old in Cardiff last term. The teenager was excluded from Willows High School, but kept returning. He faces arrest and a possible five-year jail term if he breaks the terms.
But evidence suggests that young people who commit crimes at school are often unhappy at home, and could even be the victims of domestic abuse. Experts say it needs to be made easier for schools to report disruptive pupils to social workers and police, who should then investigate their home lives.
In Bridgend, which suffered a spate of suicides among young people in 2007, a scheme is making pupil referrals to social workers and police easier for teachers. Conway Hawkins, co-ordinator of the anti-social behaviour project, said schools had their support and fewer pupils were being excluded.
"We are finding that the worst-behaved young people in schools are also badly behaved in their communities," he said. "If we can support these children - and keep them in school - it is the best option. This could have a positive effect on their communities."
Fifty Asbos were issued to under-18s in Wales during 2006, mostly for incidents outside school. But Keith Towler, children's commissioner, wants the court orders - which can be given to anyone over the age of 10 - to be banned for all children.
Professor Martin Innes, director of the Universities' Police Science Institute at Cardiff University, told TES Cymru that school buildings and grounds were one of the main targets for vandalism and abusive behaviour, but that teachers were sometimes at a loss to help young people with their troubles.
"Teachers know who the problem kids are, and that they need support, but being able to share information is often difficult," he said.
According to the 2007-08 British Crime Survey, 40 per cent of people think a lack of discipline in school is a major cause of crime. In response to this, the Church in Wales and South Wales police organised a summit at the end of last term, inviting teachers and academics to find solutions.
Governing bodies have a duty to promote good behaviour in their schools and are expected to produce a behaviour policy in consultation with pupils and parents.
But last April, the National Behaviour and Attendance Review reported that poor behaviour and high absenteeism urgently needed addressing in Wales's schools.
However, the authors of the review believed heavy-handed methods, such as exclusions, asbos or parenting orders, were not a lasting solution. They thought schools should be given more help to tackle the problem, including specialised training for teachers.
Schools are using more innovative methods, including "restorative justice", whereby conflicts are resolved through discussion.
John Sam Jones, chair of the All Wales Advisory Service for personal and social education, believes anti-social behaviour is best tackled across the curriculum, and by a positive school atmosphere.
"If the ethos is around self respect and respect for others, you have a foundation for addressing anti-social behaviour from school," he said.