Further education colleges are lobbying Parliament to demand the same funding as school sixth forms.
Colleges are warning of possible course closures
The Association of Colleges says its members receive 10% less per student from the government.
It claims courses for adults - less of a priority than those for young people - will have to be cut and that higher fees will have to be charged.
But the government said college funding was increasing at a faster rate than that for sixth forms.
'Close the gap'
AoC chief executive John Brennan said: "Colleges from across the country demand fair funding for older and younger students alike.
"The average college would gain over £500,000 per year if the funding gap between school sixth forms and colleges were closed."
Several celebrity supporters, including comedian and writer Stephen Fry, have joined the AoC's campaign for parity of funding.
'Quality of life'
Organisations including Help the Aged and the National Federation of Women's Institutes are supporting the lobbying of MPs.
David Sinclair, Help the Aged's social inclusion manager, said; "At a time when we are all being encouraged to work for longer, colleges provide essential courses for older people which can help get them get back to work and keep them in employment.
"College courses also help older people keep active and for many play a vital part in their quality of life."
A Department for Education and Skills spokesman said: "The government has increased funding for colleges.
"Funding rates per course have been rising faster than school sixth forms."