The combined opposition in the Dáil have joined forces to bring forward a motion demanding that the Government provides children with assessments of need within six months.
This is the requirement set out in a law passed in 2005, but there are now 15,296 children overdue their assessment of need.
Children are unable to access therapies in the public system until they get this assessment.
In the first three months of this year, only 7% of assessments were carried out within the required six-month period.
Next Tuesday, 14-year-old Cara Darmody will begin a 50-hour protest outside Leinster House to highlight this issue.
Inside the Dáil chamber, the opposition leaders will speak during the joint motion, which will be scheduled during Sinn Féin's private members time.
The move illustrates again that opposition parties are increasingly working closely together on issues in the 34th Dáil.
The Minister for Children has pledged to reform the assessment of need process and is working on legislation to ensure children receive therapies quicker.
Norma Foley said she fully acknowledges that the waiting lists are far too long and this is having a significant impact on the lives of children and their families.
