A Cornwall MP has urged people in the county to describe their nationality as Cornish in the 2011 Census.
The government survey is currently being posted to UK households.
Stephen Gilbert, the Lib Dem MP for Newquay and St Austell, said there were a number of Census questions in which people could describe themselves as Cornish.
A spokesman for Census 2011 said: "The form enables people to record their identities in any way they wish."
Mr Gilbert said residents could describe themselves as Cornish on sections of the form including country of birth, ethnic group and national identity.
Calls to have Cornish registered as an official British nationality in the Census were rejected by MPs in 2009.
Mr Gilbert said: "I am proud to call myself a Cornishman - I was born and bred in Cornwall and it will always be my home.
"On Census Day at the end of this month I will be recording my nationality, place of birth and, importantly, my ethnicity as Cornish.
"If enough people describe themselves as Cornish, it will massively aide the local community in fighting for greater recognition of the area's heritage and importance."
A spokesman for Census 2011 said: "The Census just provides a range of options for people to describe themselves.
"If people wish to describe themselves as Cornish then that will be recorded and counted.
"The form enables people to record their identities in any way they wish."
In 2009 a Facebook campaign calling for Cornish to be registered as a nationality in the 2011 Census was backed by more than 3,000 people.
But a commons motion in favour of it was defeated.
The Census, which is used to provide information about people living in the UK and help plan public services, takes place every ten years and is compulsory.
People are asked questions about their jobs, health, education and ethnic background.
Their answers must be based on who is in their household on Census Day, Sunday 27 March.