It was claimed that long-term damage from child abuse, poverty and bad parenting were often irreversible because other professionals on the frontline still "did not see it as their problem".
But education unions responded with "intense frustration" this week, saying attempts by concerned headteachers to pass on information to other agencies were often met with delays, with little or no feedback.
Phil Hodgson, corporate director of social services at Blaenau Gwent Council, said local government faced a real challenge as the number of looked-after children on child protection registers rose. Speaking to the Children in Wales conference, Mr Hodgson said attitudes had to change to stop long-term damage to disadvantaged children.
But Anna Brychan, Welsh director of the national association of headteachers Cymru, said: "There is widespread support for more inter-agency co-operation among our member heads who say they often feel caught in the middle. It is felt current ideas for joined-up thinking and multi-agency work are not working."
Delegates also heard from Dr Mike Shooter, president-elect of Children in Wales and a leading child psychologist, who indicated schools, social workers and health professionals needed to become a single service with a common aid.
Dr Shooter said: "We need to have a co-ordinated single service, as well as oomph and passion."
The conference had been organised to look at how more children with wide-ranging problems could be helped.
Matthew Taylor from Voices from Care (Cymru), a charity which represents children in the care system, warned that early intervention was necessary, but it needed to be sensitively handled. He said: "Young people can view intervention very negatively. They need to feel a part of what is happening to them."
Early intervention is high on the Assembly government's agenda. Its flagship policies include Flying Start, targeting children up to age three in Wales's most deprived areas and the Foundation Phase for three to seven-year-olds.
Jane Davidson, minister for education, lifelong learning and skills, said:
"We are committed to the principle that the earlier the intervention, the higher the chance of success."