On Wednesday at Buckingham Palace the brothers will unveil details of The Queen's Young Leaders Programme which aims to find future Commonwealth leaders.
The Queen is the head of the Commonwealth - the voluntary association of 53 countries made up of 2.2 billion citizens - and the position will one pass to William.
Prince Harry and Prince William carry out a joint engagemnt on behalf of their grandmother next week
It isn't the first time that William and Harry have represented their grandmother.
The pair carried out duties during her Diamond Jubilee celebrations in 2012, with William and the Duchess of Cambridge, née Kate Middleton, visiting Malaysia, Singapore and the Solomon Islands, while Harry attended events in Jamaica, Belize, and the Bahamas.
In August the duo have further oficial duties scheduled. The Duke and Duchess of Cambridge will travel to Belgium to attend a service of rememberance, before being joined by Prince Harry at St Symphorien Military Cemetery, a Commonwealth War Graves Commission cemetery near Mons, Belgium, for a UK commemorative event.
This year marks a hundred years since the beginning of WWI and the British royals have been undertaking various engagements to pay their respects.
Prince Harry, the Duchess of Cambridge, and Prince William at 2014's Trooping The Colour
British ambassador to Belgium, Jonathan Brenton, said: "I am absolutely delighted that The Duke and Duchess of Cambridge and Prince Harry are coming to Belgium for the First World War Centenary commemorations this August.
"These commemorations remind us of the important bond between our two countries and the sacrifices we shared together one hundred years ago.
He added: "It is vital that younger generations learn the lessons of the war by visiting memorials like St Symphorien near Mons, lest we forget".