Easter is a big celebration in the Royal Family and all generations join together to attend a traditional church service.
Fans are hoping to see the Queen, Kate, William, Eugenie and the rest of the gang tomorrow morning - but Meghan Markle and Prince Harry will probably give it a miss as they're expecting their first child any day now.
But last year things didn't run as smoothly as planned, and it was all because of the Duke and Duchess of Cambridge.
They arrived late to the service, which was held at St George’s Chapel in Windsor Castle, but it wasn't really their fault.
Meghan Markle praised for making very 'smart' decision ahead of royal baby's birth
It's understood they got caught in traffic on the M4 after spending a few days with Kate's family with Prince George and Princess Charlotte, reports Hello magazine .
But this meant they arrived after the Queen, which is a big no no when it comes to the royal rules.
Prince William works out with school mums after dropping kids off - at same gym Diana went to
Protocol states that the most senior member of the royal family should always arrive last.
Tut tut.
Why Zara Tindall isn't a princess but her younger cousins Beatrice and Eugenie are
Kate was technically on maternity leave ahead of welcoming Prince Louis, but attended the service as it's not an official event.
Her last formal visit was at London's Olympic Park in Stratford, east London, shortly before as part of engagements celebrating the Commonwealth.
Prince Harry and his then-fiancée Meghan Markle missed the service, which was held at their wedding venue, and Kensington Palace said this was because they had "private" plans.
Prince Philip also missed the celebration because he is suffering from a hip problem.
