Large classes and lack of places for local children were an enormous problem in growing urban suburbs, Labour spokeswoman on education Jan O'Sullivan told the Dáil.
She said school principals were put in the "catch-22" position of having to either expand their classes to way beyond capacity and good educational guidelines or turn away local children from their schools.
"This has reached crisis point for many communities around Dublin."
She said there were health and safety issues surrounding so many children cramped into classrooms.
At second level it was a major concern for the more practical subjects like science, art, technological subjects, home economics and PE.
Ms O'Sullivan was moving a Labour Private Member's motion calling on the Government to set out a timetable to meet its commitment on class sizes given in the Programme for Government.
The situation was no insoluble, she said, adding that it needed more teachers and classrooms. "At primary level there will be 1,694 new graduates this year, with others seeking to come in from other EU countries."
Ms O'Sullivan said class size was not an abstract numbers game. "The school system is failing many children in Ireland, giving them a negative experience, a negative self-image and a negative attitude to the world.
"Research has shown consistently that outcomes for young people, particularly those who are disadvantaged or have learning difficulties, are much better if they are in small classes."
Minister for Education Mary Hanafin said the Government's record was one of action and in stark contrast to that of the rainbow government which had proposed to cut teacher numbers in 1997.
She said since 1997 over 4,000 additional teaching posts had been created in primary schools.
The annual estimated value of the additional expenditure on those posts was over €200 million.
"These teaching posts have been used to provide additional resources for disadvantaged pupils and children with special needs, to reduce the pupil-teacher ratio and reduce class size."
