William's father, Prince Charles, was present at the birth of his two sons, who were born in a hospital rather than a palace both breaks from royal tradition. But William is the first senior royal to receive statutory paternity leave, which was introduced in Britain in 2003.
Some family campaigners say William, a Royal Air Force search-and-rescue helicopter pilot, is setting a good example in a country where until recently new fathers have taken little time off.
But others say two weeks is not enough, and argue social and economic pressures still discourage fathers from spending time looking after their newborns.
"There is an element that employers and men themselves are thinking of them as the ones who earn the money and stick in that role when children come along," said Jeremy Davies of the Fatherhood Institute think tank. "It can be quite difficult to set yourself apart from that."
Under British law, William is entitled to two weeks off at a flat pay rate of just under 137 pounds ($206) a week.
He's lucky the military is among employers that pay more, and he will receive his full salary for the fortnight.