The royal trio arrived in the town of Arosa earlier today for a friend's wedding and were spotted hitting the ski slopes of the Swiss Alps later in the day.
The pregnant princess was snapped laughing and smiling with pals and carrying a snow sled while dressed in dark winter coat. Middleton, William and Harry (seen here on a different ski trip) reportedly ate lunch with other wedding guests on the terrace of the mountainside restaurant Tschuggenhütte.
The royals are scheduled to attend the wedding of the princes' Olympian polo pal Mark Tomlinson tomorrow to fellow Olympian dressage rider Laura Bechtolsheimer.
The two will reportedly exchange vows on Saturday at a Lutheran church in front of around 250 wedding guests.
—Reporting by Melanie Bromley