Bad behaviour on buses does not necessarily lead to accidents but can mean extremely unpleasant journies for young people, MPs were told this week.
Martin Ward, deputy general secretary of the Secondary Heads Association, told the House of Commons education select committee that parents would not want to put their children in a situation where they were unhappy or at risk.
He said: "This is not just about safety. (Misbehaviour) doesn't lead to accidents on a daily basis but it is extremely unpleasant for many young people and they resist being put on the bus."
Just last month a report from the Commons transport committee said school buses were often so decrepit they put children off using public transport.
The committee said the school transport Bill, which includes allowing local councils to charge for travel, was too weak to tackle the crisis in education transport.
It said the Department for Education and Skills should offer incentives to classroom assistants to be escorts on school buses. Unison, the union which represents classroom assistants, is not opposed to this.
Up to 20 local authorities in England and six in Wales will trial new methods from 2006 to cut school-run traffic.
As well as charging fares and using the cash raised to improve pupil transport, the Bill would also allow selected authorities to stagger school opening and closing times.