Kate Middleton and Prince William have marked a royal first on Halloween.

On Saturday, Oct. 31, the Princess and Prince of Wales shared their first-ever Halloween-themed post on social media.

Through their joint Instagram account, Kate and William, both 44, posted a throwback photograph of their youngest child, Prince Louis, celebrating the annual holiday.

“Happy Halloween! 🎃,” the royal couple wrote in their caption, adding that the image was taken by Kate when Louis was age 1.

In the photograph, Prince Louis, now 8 years old, can be seen bending down to pick up a large pumpkin in front of him.

Princess Kate and Prince William have celebrated Halloween with their three children — Prince Louis, plus son Prince George, 13, and daughter Princess Charlotte, 11 — in years past.

Back in 2022, London resident Jay Rutland shared a photo of the Princess of Wales taking her three children to collect candy on Halloween, according to Hello! magazine.

“For anyone doubting how down to earth William and Kate are… This is Kate with their kids knocking on our door in London trick-or-treating at Halloween,” Rutland captioned the photo, the outlet reported.

Prior to that, in 2019, Kate was spotted in a local supermarket in Norfolk with Prince George and Princess Charlotte picking out Halloween costumes.

Local resident Kathy Whittaker spotted the royal browsing the holiday section, and she told several U.K. newspapers at the time, “I didn’t see what she actually bought. The lady that told me she was there had children with her, and she said Kate was asking her children what they were going to be for Halloween.”