Click on the photo for ten defining images of her life as a royal
As she reflects on her time as a royal, Kate can count the successes - the joy of the royal wedding, tours of Canada and the Far East and the pomp and ceremony of the Diamond Jubilee.
There've also been a couple of roadbumps for Prince William's wife - her debilitating morning sickness and the publication of intimate photographs of her on holiday.
Now there are new challenges ahead: making sure her son is well cared for and consolidating the couple's grand new home behind the gates of Kensington Palace.
"She is a new mother and that is the most important thing for her in the next few months, to get it right as a mother," an aide told one newspaper. "She is learning how to be a working mother."
Take a look at this special report on her key moments so far.