The newlyweds were on hand to give Queen Elizabeth their backing as her horse, Carlton House, was listed as the favorite to win the Epsom Derby.
It was the couple’s first public outing since they returned from their honeymoon in the Seychelles.
Kate, 29, chose a cream outfit to step out into the spring sunshine, while William (like his brother Prince Harry) was in traditional tailcoat and top hat, worn by men in the royal enclosure.
The previous sighting of the couple was a behind-closed-doors meeting with President and Mrs. Obama when they visited the U.K. in late May.
Unfortunately, the newly-minted Duke and Duchess of Cambridge didn’t bring any luck – the Queen’s horse came in third.
William, 28, and Kate were at the race course in Epsom, Surrey, along with Harry, 26, and their cousins Princesses Beatrice and Eugenie.
And they weren’t the only members of April’s wedding party at the races. Kate’s parents Carole and Michael were there too – to cheer on Sohraab, a horse in which they have a part share, who came in fourth in the 3:15 p.m. race.
As the rest of the family had their eyes on the horses, Kate’s sister Pippa was taking part in a grueling triathlon in Oxfordshire.
Earlier, William had taken part in a full dress rehearsal for next weekend’s official celebrations of the Queen’s 85th birthday. Wearing a tall, bearskin hat, he also sported the red tunic of the Irish guards – the same uniform William wore to his wedding.
In next Saturday’s event – called Trooping the Color – senior royals in full ceremonial dress will join military parades to mark the occasion. The following day, the family will gather at Windsor to mark another landmark, the 90th birthday of the Queen’s husband, Prince Philip.