Let the parties begin!
Kate Middleton joined Prince William and Prince Harry for her final official engagement of the year at the Youth Helpline The Mix with Heads Together Christmas party in London Monday.
Related: Kate & William Will Celebrate X-Mas With The Middletons
The Duchess of Cambridge was very festive and Christmas-appropriate in a red and green floral print Vanessa Seward dress. She's never worn this one before!
From afar, the frock looked like it was covered in holly, which is just beyond perfect for the season.
The royal accessorized with a wide, waist-cinching belt and black pumps.
William and Harry were less festive in navy suits, but we'll forgive them, we guess.
Fun fact: Drew Barrymore wore the same dress in Hong Kong a few months ago!
Check out more pics in the gallery (above)!
[Image via WENN.]
Tags: drew barrymore, fashion smashion, heads together, kate middleton, prince harry, prince william, royals royce, vanessa seward, youth helpline the mix