Parents of children who cannot access school places appropriate for their additional needs are staging a 24-hour protest outside Leinster House.
The overnight sleep-out demonstration coincides with World Autism Day and comes just over a month after a similar action outside the Department of Education.
Protesters chanted and held up placards as a series of speakers told their personal stories to the large crowd, often involving increasing stress and repeated rejection notifications.
Participants said they would "fight for every child" that needs a school place.
Those taking part called for urgent Government intervention to provide school places for all children currently without them.
Parents expressed concern over how a lack of an appropriate school place will affect their child during a crucial stage of their development.
They also raised concerns about long waiting lists for assessments of need and the level of supports for carers.
One Dublin mother said she has been met with "rejection after rejection" while trying to get a school place for her child, who has a diagnosis of autism and global developmental delay.
Jasmine Graham's six-year-old son Lewis Rock has been out of education for two years due to schools being oversubscribed.
She said Lewis requires an ASD class, a speech therapist, and a special needs assistant.
Ms Graham said: "Two years ago, Lewis was asked to leave his pre-school because they didn't have the resources for him.
"Two years later, he hasn't had any action to education - not one bit."
She added: "He is so, so intelligent and he is not getting the support he needs to thrive."
When Lewis lost his school place, Ms Graham had to leave her job to look after him.
She said the search for a school place for Lewis is "stressful" on the whole family.
She added: "We also have a new baby at home and we can't give her the time that she needs as we're constantly catering to Lewis' needs as well.
"That has a detrimental effect on our family."
Ms Graham said a lack of an inappropriate school place was in conflict with his right to an education.
She said: "Where are the classrooms, where are the resources? The delay in placing children is not just an inconvenience - it's harmful to their mental health, it's harmful to their future prospects, and harmful to the families who are being forced to navigate a system that seems to care more about cutting costs than children who are our future."
She added: "People here are looking around panicking. In an island this well established, as rich as we are, yet we are standing here at the gates of the Dail protesting for our children in 2025.
"This Government should be ashamed. So I called today to the head honchos inside to step up, and please do what is right by our children.
"We're not going to stop until every child gets what they deserve."
Rachel Kane, who is part of the North Inner City Side By Side community voluntary group, said she knows a lot of parents who have yet to find a place.
She added: "We're fighting to get school places for those children."
Ms Kane said she considered herself lucky that her 11-year-old daughter had found an appropriate school place this year.
However, she said she was now having to search for an appropriate secondary-school place.
Natalie Daly, from Coolock, said she has received 15 rejection letters while searching for a place for her four-year-old son Levi-Jai.
"He's diagnosed with autism, he's non-verbal and he's on his 15th refusal for a special needs class or ASD unit," she added.
She said she did not realise how severe the problem of a lack of school places was until she attended the last sleep-out protest.
Ms Daly described the experience of trying to secure the appropriate supports for her son as a "constant fight".
She said: "It's very hard on your mental health, i'ts very tiring. Every day is a fight for something.
"He's coming up to five and he hasn't even had a speech and language session, do you know what I mean? It's a constant fight for everything.
"You spend most of your day ringing people, sending emails, trying to fight for even the therapies - never mind even the school places."
Like other parents in the same situation, she is worried about the impact on Levi-Jai's development.
She added: "They say early intervention is key. Sure, he’s not even getting early intervention.
"On top of your normal worries, I worry about if something was to happen to me - who is going to take him on, he's non-verbal."