Kate, 34, was on hand at the former home of Henry VIII to officially open a brand new children's attraction called the Magic Garden, a play area inspired by the myths and legends of the Tudor Court.
It's set among Henry VIII's former Tiltyard and features battlements, towers, mythical beasts and a secret grotto.
Kate didn't bring her own children, Prince George, two, and Princess Charlotte, one, along for the day, but she did spend time with a group of children who were at the palace enjoying the Magic Garden. She knelt down to chat with the kids and play in the sand.
She looked lovely (as per usual) in a blue tweed Michael Kors coat which may look familiar to some, as she previously wore the garment during a visit to the Australian War Memorial in Canberra in 2014.
It was the first of three engagements for Kate today: she'll also attend a lunch at the Anna Freud Centre in London, as well as viewing the Vogue 100: A Century of Style exhibition at the National Portrait Gallery this evening.
Kate is a patron for Anna Freud, which provides support and resources for children's mental health, and a patron for National Portrait Gallery. She appears on the cover of Vogue magazine's 100th edition, in a series of photos shot near her Norfolk home by photographer Josh Olins, in collaboration with the gallery.
Try Reveal's digital edition on iPhone & iPad. Subscribe now & never miss an issue!