Kensington Palace has confirmed Prince George and Princess Charlotte will join their parents on a royal engagement abroad for the first time.
The Duke and Duchess of Cambridge will be travelling to Canada between September 24 and October 1.
In a statement, the Palace said William and Catherine "look forward to having the chance to introduce their young family to the country."
A busy week will see the couple attend more than 30 engagements in British Colombia and Yukon.
They will meet a wide range of people, including young Canadian leaders in business, film, sport, and music, members of the Canadian Rangers, Syrian refugees and some of the staff and volunteers who support the 25,000 migrants who arrive in Canada each year.
In Vancouver, they will meet the team at a charity that works with mothers who are battling addiction.
On Thursday, September 29, a children's party will be held in Victoria's Government House which the couple will attend with Charlotte and George.
This will be 16-month-old Charlotte's first trip abroad and three-year-old George's second: he accompanied his parents to Australia and New Zealand in 2014 when he was just eight months old.