The Duchess of Cornwall is to join her local Women's Institute in Tetbury near her home at Highgrove, Gloucestershire.
The Duchess is on a tour with her husband Prince Charles in Egypt
She will be the latest in a line of Royal WI members, which have included Queen Alexandra, Queen Mary and the Queen Mother.
Judi Mason-Smith, President of Tetbury WI, said: "We are honoured that Her Royal Highness is joining us.
"We would be pleased to welcome her at any of our meetings and to keep her in touch with everything we are doing."
The Duchess is said to have became interested in the WI when she met former National Chairman Barbara Gill and some of the women who inspired the Calendar Girls film at a function at Clarence House.
The film was based on members of a Yorkshire WI who posed nude for a calendar for charity.
Princess Anne, who lives at Gatcombe Park not far from the Duchess, is also a Gloucestershire member.
Chairman of Gloucestershire Federation of WIs, Gill Thomas, said: "The WI is the largest independent women's organisation in the country.
"We strive to improve the world around us and having Her Royal Highness as a member in Gloucestershire will only help us to further our aims. We are both delighted and honoured that she is keen to be involved with us."
The Duchess and the Prince of Wales are currently on a trip to Egypt.