People are being urged to sign a petition that will help get a school's plight discussed at a council meeting.
Heene First School in Norfolk Road, Worthing, needs to find space to accommodate extra classrooms when it becomes a primary school from September 2015.
The school plans to build on its existing playground – a move parents say will reduce it to “almost nothing”.
Instead, parents say expanding on the site of an old pub which backs on to the school would prove a better option.
But the land has been subject to a planning application from developers who want to build a block of flats.
Now parents and guardians at the school are calling for thousands of signatures on a petition that will help get their situation discussed at the next West Sussex County Council meeting.
They hope the council will intervene and fund an alternative option for the site.
The petition needs 3,000 signatures by Thursday July 10, 15 days before the meeting.