School pupils can be registered as "Cornish" in a national educational survey, the government has said.
The aim is to enable education officials to study the progress made in schools by children from different ethnic backgrounds.
The Department for Education and Skills was criticised when it failed to list Cornish among ethnic categories for school pupils.
The turnaround follows lobbying by campaigners from Cornwall.
Cornwall County Council says one of the aims of the survey is to see how pupils in urban areas whose first language is not English are getting on.
Cornwall has a unique history that should be recognised in schools
Other ethnic categories listed include travellers of Irish heritage and Gypsies.
Letters with details of the new policy are being sent to the parents of Cornwall's 74,000 school students.
Matthew Clarke from the Cornish Language Fellowship said: "It's a victory for commonsense.
"You have to realise that the Cornish have been here for longer than the English and it has taken all this time for people to come round to that.
"Cornwall has a unique history that should be recognised in schools."