Delegates at the Association of Secondary Teachers in Ireland convention in Sligo have unanimously passed a motion to establish a policy of maximum class size of 20 for all subjects.
A call for this policy to be implemented from the start of the 2008 school year is included in the motion.
In his address to delegates, ASTI President Michael Freeley said large class size is a major factor in making teachers' jobs more difficult and he said it is also adding to discipline problems.
He also highlighted the challenge facing teachers in coping with a multi-cultural society and called for many more language support teachers to facilitate meaningful integration.
Mainstreaming of students with special educational needs is also another huge challenge for our schools, Mr Freeley said.
He added that the overwhelming majority of teachers have never received any training or in-service in relation to this mainstreaming.
Earlier, the Minister for Education, Mary Hanafin, reiterated that if returned to power the Government will continue to reduce the size of classes until it reaches an average of 24 pupils.
Ms Hanafin said the Government hopes to achieve this in the first three years of a new Dáil.
Meanwhile, the ASTI has also unanimously passed an emergency motion calling on the Irish Congress of Trade Unions to renegotiate the pay terms of the social partnership agreement, Towards 2016.
Mary Hanafin told RTÉ News the Government had no intention of renegotiating the agreement, and the issue of pay for second level teachers could be dealt with in the context of benchmarking.
She said that if Fianna Fáil is returned to Government it will double the amount of funding per primary school child.
Speaking at the annual Irish National Teachers' Organisation conference, the minister promised to double the State's capitation grants from €163.50 per year per child to €327.
