Druidry is to become the first pagan practice to be given official recognition as a religion.
The Charity Commission has accepted that druids' worship of natural spirits could be seen as religious activity.
The Druid Network's charitable status entitles it to tax breaks, but the organisation says it does not earn enough to benefit from this.
The commission says the network's work in promoting druidry as a religion is in the public interest.
The move comes thousands of years after the first druids worshipped in Britain.
Druidry was one the first known spiritual practices in Britain, and druids existed in Celtic societies elsewhere in Europe as well.
Phil Ryder, chairman of the trustees of the Druid Network told the BBC: "It's nice to have that official recognition. It's not why we applied originally.
"We applied because we were legally obliged to do so."
He said the organisation represented around 350 people who had paid £10 each for membership but referred to a BBC Inside Out investigation from 2003 which suggested that up to 10,000 people described themselves as druids.
He added: "You have to apply [for charitable status] if you're an organisation that is taking money off people because the Inland Revenue want to know what you're doing with it."
BBC religious affairs correspondent Robert Pigott says that with concern for the environment growing and the influence of mainstream faiths waning, druidry is flourishing more now than at any time since the arrival of Christianity.
Druidry's followers are not restricted to one god or creator, but worship the spirit they believe inhabits the earth and forces of nature such as thunder.
Druids also worship the spirits of places, such as mountains and rivers, with rituals focused particularly on the turning of the seasons.
After a four-year inquiry, the Charity Commission decided that druidry offered coherent practices for the worship of a supreme being, and provided a beneficial moral framework.
The decision will also mean that druidry will have the status of a genuine faith.
Referring to the tax breaks, Mr Ryder said: "For us that is a very small consideration because we don't really have that level of income to make that even an issue."
He said what was more important was that it would make administrative tasks a lot easier for the organisation.
"It does give recognition with local councils and people who provide premises and services to charities, who will only deal with registered charities," he said.
Senior druid King Arthur Pendragon, told the BBC News website the organisation had had to "jump through hoops" to meet the commission's requirements.
Although he runs his own druid order, he said the Druid Network's achievement was a celebration for all members of the faith.
He said: "We are looking at the indigenous religion of these isles - it's not a new religion but one of the oldest."
The 56-year-old added that people were becoming more interested in finding spirituality and the decision reflected this.
"I think people are looking to their roots and looking back at the secular world certain that things don't work.
"This decision shows how important our faith is. We are getting credence from a secular government about our belief structure - which not only shows it is valuable but also valued by us and others."
Mr Pendragon, of Stonehenge, said he would not be seeking charitable status for his own order - the Loyal Arthurian Warband - as it was a political wing and therefore had no need to be recognised as a charity.