The Queen's sixth great-grandchild has been christened in a service at St James's Palace this afternoon.
Prince Louis was baptised by the Archbishop of Canterbury, Justin Welby.
The 11-week-old baby son of William and Kate was carried into the chapel by the Duchess of Cambridge and wrapped in a replica of the Royal Christening Robe - the original was made in 1841 for the christening of Queen Victoria's eldest daughter.
It's the first time the Cambridges have been seen as a family of five since Louis was born on April 23.
Both sets of Louis' grandparents were at the Chapel Royal inside St James's Palace, Prince Charles and Camilla and Michael and Carole Middleton, as well as Uncle Harry and Aunty Meghan.
The then Meghan Markle was baptised here by Justin Welby just a few weeks before her wedding.
Both she and her husband Prince Harry shared a joke with the Archbishop before the service.
William and Kate chose six godparents for their third child.
They are all friends or family of the Duke and Duchess and include the nightclub owner Guy Pelly and Kate's cousin Lucy Middleton.
The Queen was not present today. She travelled back from Sandringham earlier, where she spent the weekend.
The 92-year-old has a busy schedule this week including a meeting with US President Donald Trump on Friday.
The Crown Jewels cupboard was opened for the christening.
The silver baptismal font, the Lily Font, was first used in 1841 and has been a feature of Royal Christenings since then.
Tea and cake is being served at Clarence House afterwards.
William and Kate have followed tradition by reserving a tier from their 2011 wedding cake.
Which means the cake being offered to guests is seven years old!