Only one primary school in four receives a psychology service from the Department of Education and Science, the head of the service has said.
About 2,000 primary-school pupils will be assessed by the expanded service this year, but a recent Eastern Health Board report suggests six times that number may suffer from Attention Deficit Hyperactivity Disorder alone.
It also makes it clear that intervention at primary-school level is the best way to help these and other children with special needs.
The Eastern Health Board closed its waiting list for educational psychology services in April. One reason was that the list was so long, EHB officials argued they were creating false expectations by adding to it.
The EHB service was used by schools in Dublin, Kildare and Wicklow, which were not designated to get a service from the Department.
The waiting list is still closed and some children who were on it are still waiting.
The loss of the service means many schools which want to apply to the Department for funding to set up special classes have to pay for psychological assessments themselves, or ask parents to pay.
Without an assessment, their applications will not be considered.
These schools include one in Tallaght which has 900 pupils and no educational psychology service.
Another reason given for the closure of the EHB service was the expectation that the new National Educational Psychological Service Agency would take over its work. However, it has become clear this will not happen in the short term.
The agency started in September. Its job is to provide the service previously provided by the Department.
Its acting director is Ms Lee MacCurtain, who previously headed the Department's service, and it has inherited 42 psychologists from the Department.
By the end of this school year it will recruit another 50 and plans A agency. Primary schools only began to get a service in 1990.
The present Minister, Mr Micheal Martin, has set about expanding the service substantially.
"We are very well aware of the dilemma, and it's most unfortunate," Ms MacCurtain said of those schools, which have to pay for assessments out of their own funds when applying to the Department for special classes or special teachers.
These schools also miss out on the advisory and other support services which a minority of primary schools get from the agency.
St Kilian's junior and senior national schools in Castleview, Tallaght, have 900 pupils between them and no educational psychology service, according to Mr Garrett Edge, principal of the senior school.
"The only service we had was given through the Eastern Health Board," he said.
"We have children who are emotionally disturbed and some other children who need help.
"If we want to apply for special services for any child we must accompany the application with a psychological or medical report.
"If we don't produce the papers, the application isn't even considered."
He also criticised the level of help given even when an application is approved.
"If I had a visually impaired child, that child would be worth one-eighth of a teacher."
One principal told The Irish Times that his school is allocated four hours per week of a special teacher's time for an emotionally disturbed child.
This allocation is completely inadequate, he said.
The shortage of educational psychologists has made itself felt in other ways. The Minister recently told the Fine Gael TD, Mr Brian Hayes, that this year extra psychologists had to be brought in on contracts to clear a backlog of assessments needed by pupils seeking special arrangements for the Junior and Leaving Certificate examinations. The same could happen again, he acknowledged.