Campaigners have called for a commitment to complete the building of Woodlands Meed School.
The special school in Chanctonbury Road, Burgess Hill, opened in 2012 but funding to build a college has never surfaced.
As such, older children are educated at Birchwood Grove Road, in an old prefabricated building.
A recent meeting of the Central & South Mid Sussex County Local Committee saw dozens of parents and supporters pack into Haywards Heath Library to demand to know why they had received no updates on the situation for a year.
Questions during the Talk With Us open forum ranged from tearful to concerned to angry and there was an air of frustration when committee chairman Councillor Peter Bradbury (Con, Cuckfield & Lucastes) explained that none of the members had the executive powers to take action.
It was acknowledged that more communication about the future of the school was needed between the council and parents.
Former governor John Clifton said: “The county council is responsible for completing the build.
“We as parents, as governors, as members of the local community, hold you responsible for getting this job finished.”
Mr Bradbury said he “strongly recommended” that Councillor Richard Burrett, the county council’s Cabinet member for education and skills, should visit Woodlands Meed.
He said: “We have noted all the comments and will minute those and pass them to the Cabinet member for his consideration and ask him to take note of the strong depth of feeling.”
Mr Burrett is due to meeting school governors later this month.
While delighted with the turnout at the meeting, members of the Complete Woodlands Meed campaign said they were disappointed to have received no direct answers to their questions.
A spokesman for the campaign said: “We expect Richard Burrett, post his meeting with the governors, to inform campaign supporters of his commitment to a full
new build of the college together with the supporting strategy and plans before Easter 2018.
“If not we will be knocking on his door.”
Mr Burrett said: "Woodlands Meed has been a significant focus of my attention since I took on my current role in May last year. I have been working closely with our Director of Education and Skills to look at all possible options. I look forward to the meeting with governors and will inform parents, carers and the wider community of developments as soon as I am able to.”