Kate and Prince William will have to leave their son at home while they attend an awards ceremony for a British charity as guests of honour.
Kensington Palace confirmed the news that Kate will attend the event on September 12, with a spokesperson saying: "It is a long standing engagement".
It's pretty likely K-Middy's mum Carole will take care of the royal baby while the couple head out for the evening - after all she is the ONLY one who can get the new prince to sleep.
Earlier this week, dad Wills gushed about his first born son at the Anglesey Show in Wales, telling the crowd that his three-week-old son is "pretty loud and of course very good looking". He also joshed about the challenges of taking care of a new baby.
"I have to say that I though search and rescue duties over Snowdonia were physically and mentally demanding, but looking after a three-week-old baby is up there!" Bless.