Campaigners have called on the Duchy of Cornwall to increase the number of affordable homes at a site in Newquay.
Outline planning permission has been granted for up to 170 properties at the site off Tregunnel Hill.
The affordable homes quota fell with the loss of a social housing grant.
Dave Sleeman, of the town's residents' association, said young people were "screaming for a house in the town". The Duchy said it was responding to council requests to meet housing need.
Mr Sleeman added: "Buying a house in Newquay is virtually impossible.
"The building costs should be kept down, the houses should be affordable that people can go and buy."
June Fullwood, a member of the Cornwall Wildlife Trust, said the trust was concerned about the effect of the development on wildlife in the area, including badgers.
"The buildings will go to within two metres of the artificial setts and with nowhere to run they're going to leave," said Ms Fullwood.
She added: "We want people to stand shoulder to shoulder and say they've had enough. We need these green open spaces."
The Duchy Estate said it had employed a firm to manage the safe relocation of the badgers.