Kate Middleton, Prince William, and Prince Harry Attend Charity Christmas Party Together: Pics!

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The royals are in the holiday spirit.

Kate Middleton, Prince William, and Prince Harry all attended a Christmas party together on Monday hosted by youth support service The Mix in London, England, which celebrated the volunteers and counselors who support people through tough times in their lives. The Mix is a charity which offers confidential support to young people online, through social media and via a phone helpline.

Middleton looked gorgeous as always, flanked by her husband, Prince William, and her brother-in-law, Prince Harry, who both looked sharp in blue suits.

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The mother of two wore a festive red and green dress by French designer Vanessa Seward, which retails for $1245.

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At the party, the trio attended group sessions and listened attentively to counselors and volunteers. Middleton also joined a live online chat about counselling with volunteers and young people from around the UK.

Later, they made their own holiday decorations, adding words of support to paper chains.

The party comes after Prince Harry's girlfriend, Suits actress Meghan Markle, was spotted at the airport, presumably headed home for the holidays after spending time with Harry in London. This past Monday, the two were spotted Christmas tree shopping at Pines in Needles in London's Battersea Park.

The couple also enjoyed an evening out at the theater, going to see the West End production of The Curious Incident of the Dog in the Night-Time.

WATCH: Prince Harry and Meghan Markle Spotted Christmas Tree Shopping in London

Watch the video below to see Harry and Meghan's adorable first photo together!