Here are the details of the programme confirmed by royal officials:
- 8:15 am and 9:45 am (0715 GMT and 0845 GMT): The general congregation arrives at the Great North Door of Westminster Abbey.
- 9:50 am: Arrival of governors-general and prime ministers of 16 "realm countries" of which Queen Elizabeth II is monarch and head of state, including Britain, plus the global diplomatic corps, and other distinguished guests.
- 10:10 am: Prince William and Prince Harry leave Clarence House, the official residence of their father Prince Charles, arriving at Westminster Abbey at 10:15 am.
William faces a nervous wait in a side chapel of at least 45 minutes for his bride.
- 10:20 am: Members of foreign royal families arrive at the abbey from Buckingham Palace.
- Kate Middleton's mother Carole and brother James will leave the Goring Hotel, where the bride and her family will have stayed overnight, arriving at the abbey at 10:27 am.
- 10:35 am: Prince Andrew and his daughters Beatrice and Eugenie; Prince Edward and his wife Sophie; and Princess Anne and her husband Timothy Laurence leave Buckingham Palace, arriving at the abbey at 10:40 am.
- 10:38 am: Prince Charles and his wife Camilla leave Clarence House, arriving at the abbey at 10:42 am.
- 10:40 am: The Queen and Prince Philip leave Buckingham Palace. They arrive at the abbey at 10:45 am.
- 10:48 am: Bridesmaids and pages leave the Goring Hotel, arriving at the abbey at 10:55 am.
- 10:51 am: Kate Middleton and her father Michael leave the Goring Hotel.
She will travel in a claret-coloured 1977 Rolls Royce Phantom VI limousine, which was damaged and then repaired after student protesters attacked Prince Charles and Camilla in December.
Her route to the abbey passes anticipated crowds of hundreds of thousands of people in The Mall, Horse Guards Parade, Whitehall and Parliament Square.
- 11:00 am: Marriage service begins.
Archbishop of Canterbury Rowan Williams, the head of the Church of England, will marry the couple. The Bishop of London, Richard Chartres, will give the address and Dean of Westminster John Hall, the abbey's senior cleric, will conduct the service. The marriage service will be relayed by audio speakers along the route.
- 12:15 pm: The newly-weds travel by carriage to Buckingham Palace.
They will be accompanied by the Household Cavalry, followed by the queen's Procession with a Sovereign's Escort of the Household Cavalry.
If the weather is good they will use an open-topped gold 1902 State Landau coach that was used to carry Prince Charles to his wedding to Princess Diana in 1981. If it is raining they will use The Glass Coach, which carried Diana to the wedding.
The route takes William and Kate from the abbey, along Whitehall, cuts through Horse Guards parade, then goes up the Mall to Buckingham Palace, with William and Kate arriving at 12:30 pm.
The rest of the royals arrive at 12:40 pm and other guests after that.
1:25 pm: The queen and the newly-weds, together with their families, appear on the balcony of Buckingham Palace. William and Kate are expected to kiss.
1:30 pm: Flypast by Royal Air Force (RAF) jets and World War II planes from the Battle of Britain Memorial Flight.