There's been loads of speculation about their wedding details since their engagement last year, with Kate's dress, their hen and stag parties and their honeymoon locations all being kept top secret.
But here at goodtoknow we're too excited to wait so we thought we'd look at everything we do know about the Royal Wedding and the things we don't...
Date and venue
Kate and William will be tying the knot on Friday 29 April. The ceremony will be at 11am at Westminster Abbey (below), where royal celebrations have been held for years and where William's late mum Princess Diana's funeral took place. Kate will arrive at the Abbey in the Queen's Rolls-Royce, which was used at Prince Charles and Camilla's wedding.
We know that around 1,900 invitations were sent out for the ceremony, with some of the most high-profile guests including Victoria and David Beckham, Elton John and a handful of royals around the world.
Kate and Wills have, of course, invited their families and friends, with a postman, shopkeeper and pub owner from Kate's village, Bucklebury, also attending!
Someone who won't be at the wedding is Wills' former aunt Sarah Ferguson.The Obamas are also not invited.
Wills has picked his brother Prince Harry as best man and Kate has chosen her sister Pippa Middleton for her maid of honour. The bridesmaids and page boys will include the Earl and Countess of Wessex's seven-year-old daughter Lady Louise Windsor and William's godchildren Miss Grace Van. Custem and Master Thomas Pettifer.
The Queen will host Kate and William's wedding breakfast at Buckingham Palace for around 600 guests, after their procession from the Abbey to the Palace in the carriage that Princess Diana used for her and Charles' wedding.
In the evening Prince Charles will host a dinner (with dancing!) at Buckingham Palace for around 300 members of close family and friends.
We know that Kate's keeping details of her wedding dress top secret. A few top fashion designers have been said to be designing the dress, including Phillipa Lepley, Bruce Oldfield and most recently, creative director of Alexander McQueen, Sarah Burton (below).
The couple's titles
At the moment Kate Middleton has no problem being called Kate or Catherine, but once she's married, just being a Mrs won't do. And what will the couple be called? It's up to the Queen what title Kate is given but it's most likely that they will become a Duke and Duchess as Prince Charles and Camilla hold the titles of Prince and Princess of Wales and Kate and Wills are a long way off being King and Queen.
As soon as she marries, Kate will become Her Royal Highness Princess William of Wales.
Kate and Wills aren't interested in receiving a toaster or china as wedding gifts. Instead the couple are asking guests to donate cash to their chosen 26 charities. Kate was bullied at school and has chosen Beatbullying as one of the charities. Others include London Zoo, some military charities and a bereaved kids charity.
The royal couple's honeymoon destination is another of their wedding secrets, but we have received a few hints. On his recent trip to Australia Wills said: 'I will have to come back, maybe we'll have a honeymoon in Cairns?'
Where to next?
- More Royal Wedding news and events
- Kate and William's romance in pictures
- Funny Royal Wedding souvenirs