Only one in 10 headteachers believes giving staff a new "legal right to discipline" pupils will make much difference to tackling bad behaviour.
But a poll by the Association of School and College Leaders indicates that other planned laws will have a significant impact, if properly funded.
Jacqui Smith, schools minister, gave more details this week of the plans to improve behaviour, one of the few sections of the Government's education white paper that has been welcomed by teachers.
The proposals are based on recommendations last year from a taskforce of teachers led by Sir Alan Steer, head of Seven Kings school in Redbridge, London.
Ms Smith emphasised the plans would give teachers a "clear right to discipline pupils". This includes restraining pupils or confiscating inappropriate items on and off their schools' grounds. "It will mean an end to the 'Can't tell me, Miss' culture," she said.
Teachers' unions have welcomed the measures, as has Sir Alan. But Sir Alan said he was baffled by the attention politicians and the press had given to the right to discipline, as his teachers had reprimanded pupils outside their school gates for many years. Although he said greater clarity and legal protection was needed, teachers have had a right to discipline children since 1996 and powers to confiscate pupils' possessions were set by case law in 1865. "The real title of our report should have been 'Please do the obvious and do it regularly'," he said.
A small poll of 100 heads by the ASCL found that heads felt the right to discipline was the least effective of the Government's behaviour proposals.
Only 13 per cent felt it would have a significant impact. In contrast, they were optimistic about the plan for schools to work together to create on- and off-site centres for pupils who were excluded or at risk of exclusion: at least 60 per cent believed this would make a significant difference.
John Dunford, ASCL general secretary, said the Government had to make this practice widespread, but that there was no sign of extra funding for it in the white paper. "Setting up on or off-site provision is very expensive,"
he said. "It needs to be more than words in the white paper - there has to be money for it."
One of the headteachers surveyed said that they were spending pound;50,000 to pound;60,000 a year funding off-site education for pupils, which had been highly effective. But he said he would have to cut the numbers drastically next year because the fees were being increased.
Seven out of 10 of the heads said they were spending more time dealing with poor behaviour than five years ago. Many blamed changes in society, poor parenting, a lack of positive role models and a small proportion of "hardcore" misbehaving pupils who seemed oblivious to sanctions.
"My school is a grammar where you might expect few behavioural issues," one said. "However, we are definitely experiencing far more low-level disruption and also significantly more fights and theft. It seems more acceptable in society."
Another head said: "Generally poorly behaved students have poorly behaved parents who will not conform to school rules themselves. Thank God I only have 12 months left."