Second-level school principals have said the Department of Education should immediately begin planning to ensure post-primary schools can cope with an expected increase in student numbers.
It is estimated that the secondary school population will increase by 15% by 2020, with an additional 10,000 students in the system.
The National Association of Principals and Deputy Principals has said it is concerned there could be a shortage of teachers to teach particular subjects.
It said there is currently no relevant data on the types of teachers who will be retiring in coming years and what subjects they currently teach.
The NAPD also said more resources need to be made available, particularly in the area of ICT.
In a statement, NAPD director Clive Byrne said the increase would require more than just more classrooms and teachers.
It was essential that there was a correct match between subjects taught and teachers, he added.
He said in particular Ireland needed sufficient teachers to teach science, technology, engineering and maths.
He also said radical plans for Junior Cycle reform meant teachers would be needed to teach subjects such as philosophy, politics, web-design and Chinese.
The NAPD said it should be an immediate priority to begin planning for this challenge.
The Department of Education this afternoon said it has commissioned a report into the potential impact of the growing schoolgoing population on teacher numbers.
The Department says it asked the Teaching Council to look at the issue some time ago.
It says the council's report is due to be completed by the end of this year.