Prince William installed as a Knight of the Thistle
The event at the city’s St Giles’ Cathedral was attended by the Queen, accompanied by the Duke of Edinburgh, the Princess Royal, the Duchess of Cambridge and hundreds of invited guests.
Thousands of people crowded on to the Royal Mile to catch a glimpse of William and Kate - known as the Earl and Countess of Strathearn while in Scotland - and other royals as they made their way from the Signet Library, across Parliament Square and into the cathedral.
The Order of the Thistle is the highest honour in Scotland and is second only in precedence in the UK to the Order of the Garter.
It honours men and women who have held public office or who have contributed in a significant way to national life.
The Princess Royal was invested in the Order of the Thistle in June 2001.
The royal family entered the cathedral shortly before 11am to a fanfare, accompanied by other members of the Order, all wearing ceremonial gowns.
Meanwhile, the Duchess of Cambridge, wearing a pale yellow coat and hat, took her place in the audience.
The installation ceremony was conducted by the Dean of the Thistle, Rev. Gilleasbuig Macmillan.
The short ceremony took place within the internal Thistle Chapel and was broadcast through speakers to those in the cathedral.
The Queen said: “It is our pleasure that His Royal Highness the Prince William, Earl of Strathearn, be installed a Knight of the most ancient and most noble Order of the Thistle.”