Diana, Princess of Wales, holding an infant Prince William.
He was a very expressive baby! Check out those two little chompers in the front.
Always keep your ABC's close on hand, we say.
William was too cute for words in these bright blue overalls.
Just a kid, hangin' at Kensington Palace...
William with his pony named "Smokey" at home, wearing a sweet Mickey Mouse sweatshirt.
Ready for school, mom! William heads off to Wetherby School in London, dressed in his head-to-toe uniform.
William's shorts match the bright red strawberries he carries, looking delighted at a polo match.
Elegance starts at a very young age: William attends a Christmas service in a tie and peacoat.
William looks on during Carter International Polo Day, starting to look grown up!
William wears a Canadian tuxedo, denim from head to toe while visiting Toronto.
William smiles at the camera, watching the Parade of Veterans in London.
The Prince wearing his Eton school uniform at a tea party for the students.
Prince William relaxing on the banks of the River Dee, dressed in casual jeans, boat shoes and a plaid shirt.
William steps out of a Ford Focus wearing jeans and a sweater.
William relaxes at Highgrove with his father, Prince Charles.
Wills rocks a pair of wellies while repairing walkways in Southern Chile.
William arrives for his first day at St. Andrews University in Scotland.
William puts models to shame with this photoshoot of him on the beach -- playing rugby in his favorite casual look: a button up, sweater, and jeans.
A big sports buff, Polo is one of William's favorite games.
Prince William is photographed in St. James Palace, a portrait released for his 21st birthday.
William visits a farm nearby his home in Gloucestershire, the Duchy Home Farm, wearing a tweed cap and waxed jacket.
William attends a wreath laying ceremony in New Zealand, looking very sharp for the occasion.
William is looking quite dapper for the Queen's 80th birthday celebration.
William attends the Combined Calvary Parade in Hyde Park, London, wearing a grey suit and bowler hat.
Prince William decked out in his uniform during his military helicopter training course at RAF Shawbury.
William took an unofficial visit to Australia, watching soldiers fire their weapons in a blue button up and dark slacks.
A duo that always looks great (especially at weddings!), then-girlfriend Kate Middleton attends a friend's ceremony alongside William.
After dating for 8 years, William and Kate announced their engagement, both dressed sharply in dark blues.
It was a wedding for the ages, and photos of this day -- and what they were wearing -- are timeless images of a royal love story.
Quite the change! The pair wear cowboy boots and hats for a visit to the Calgary Stampede in Canada.
The Duke and Duchess attended the BAFTA Awards, dressed to the nines.
Dressed much more casually (but still perfectly put together) the duo visited Bacon's College with Prince Harry.
Baby news! Kate's morning sickness at the beginning of pregnancy forced the couple to reveal to the world quite early that they were expecting. The pair glowed in matching blues as she headed home from the hospital.
Ahh, Princely duties. Just weeks before his first baby arrives, Wills attends the Order of the Garter Service, complete with traditional garb and large feathers.
Doting dad looks good on him, don't you think? The blissful couple introduce Prince George to the world.
William was dapper in a navy suit next to his wife, wearing Alexander McQueen, for little George's Christening day.
William arrives at an army base in Aldershot, England, for a ceremony presenting medals to those who served in Afghanistan.
Prince William looks dashing at The Audi Polo Challenge.
(Photo by Mark Cuthbert/UK Press via Getty Images)
William and his family attend the Trooping the Colour ceremony with the rest of the royal family.
(Photo by Max Mumby/Indigo/Getty Images)
Prince William gets all dolled up for the annual Order of The Garter Service at St George's Chapel.
(Photo by Peter Nicholls/WPA Pool/Getty Images)
Hats, please! Duchess Kate and Prince William attend day 2 of Royal Ascot.
(Photo by Mark Cuthbert/UK Press via Getty Images)
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Happy birthday, Prince William!
Britain's second-in-line to the throne turns 34 today, just a month before his son George's third (!!) birthday.
The elder son of Prince Charles and the late Diana, Princess of Wales, William is next in line to the throne following his father. He was born on June 21, 1982, and received a brother just a few years later. Educated at four schools in the UK, he was fifteen years old when his mother passed away. He went on to attend St. Andrews University, where he would meet Kate Middleton, now his wife.
Just before he and Kate were wed on April 29, 2011, William was given the title Duke of Cambridge by the Queen. Ever since the boys were young, they had a passion for many causes -- instilled in them by their mother, Diana. William has honored her legacy by his involvement in organizations that combat disease, homelessness, children's issues and environmental problems.
Happy birthday to the Duke of Cambridge! Click through the gallery to see his style transformation.
Plus, click through below to see William and Kate's cutest moments:
William and Kate's cutest moments ever
When they became husband and wife!
When they presented Prince George to the world.
When William's team won the Foundation Polo Challenge, Kate gave him a kiss on the cheek.
At the premiere of 'African Cats,' when William held the umbrella for Kate.
When Wills helped Kate with her sweatshirt.
The day after their wedding, when they held hands as they jetted off to their honeymoon.
When William helped Kate into her seat during the Olympics. Hey, wedges are treacherous!
When they celebrated a big win for the UK!
When Prince William read Kate's nametag as she rested her hand on his knee.
When doting Prince William led his wife from the hospital, just after they announced she was pregnant.
When they had this adorable moment with George.
When William presented Kate with a flower in Australia.
When William felt the need to help Kate with her handprint-making.
How William always looks back and waits for Kate to catch up.
This impromptu hug when William beat Kate in a boat race.
When they had fun (and were clearly overheated!) during the 2014 Glasgow Commonwealth Games.
When they couldn't stop laughing during an engagement at Prince Edward island, Canada.
When Kate and William led the family to church on Christmas morning, holding hands.
When Kate beat William in a boat race. (They race a lot of boats!)
When they showed us that they have the most PERFECT FAMILY EVER.
When Prince William made a speech and Kate looked at him adorably.