The couple visited England's East Lancashire town of Darwen to open an academy and launch a Prince's Award.
When most of the U.K. enjoyed sunshine, hundreds of well-wishers lined up in Darwen in the heavy rain.
This is the last stop on a mini-tour of the nation Middleton might one day rule as queen: all carefully choreographed by royal aides.
"This is what she looks like, this is how she walks, this is how she talks, she's Kate Middleton and we think she's great," ABC News' royal contributor Duncan Larcombe said.
They are expected to be met by crowds of thousands on their second and final engagement at nearby Witton Country Park in Blackburn.
William will officially open an academy and launch an award called the SkillForce Prince's Award.
SkillForce is an education charity, and William is its patron. Starting Summer 2012, it will present the new award to teenagers who show significant character or make a major contribution to their community.
Still on the schedule for today is a visit to Witton Country Park.
This is part of the prince's role as patron of the Queen Elizabeth II Fields Challenge, an initiative that aims to protect permanently 2,012 outdoor recreational spaces across the U.K. and demonstrate the importance of green spaces for sport.
Middleton, known for her sporting prowess, will be invited to start a 100-meter race and meet a group of athletes and coaches.
"Kate looks phenomenal," royal expert Katie Nicholl, who was in Darwen, said. "She's wearing her hair half up and half down. The rumor is she might be wearing it like that for the day of the wedding itself. Maybe this is a practice run."
The final appearance of the couple before the wedding day has set tongues wagging about the guest list.
"All week there will be meetings to decide the seating plans," Nicholl said. "We revealed the guest list at the weekend. The big question is where all those people will sit."
Apparently, David Beckham and wife Victoria are on the list, as well as director Guy Ritchie, but his ex-wife, Madonna, is not.
"Lots of very big names that have surprised people," Nicholl said. "The head of PR for Audi has raised more than a few eyebrows. It's a fascinating list.
"The ex-boyfriends and ex-girlfriends are particularly interesting."
William has invited four of his exes and Middleton has invited two old flames.
And there's word that her uncle, Gary, allegedly caught with cocaine in a newspaper sting, will come to the palace reception, as well as the ceremony.
The Obamas, however, are not invited. Although the queen has asked them over in May for a state visit.
Washington billionaire Joe Allbritten has been invited at the request of Prince Charles, according to the Daily Mail. Allbritten owns U.S. TV stations and founded the Politico web site and newspaper.
Elton John is also coming; although probably not singing (as he did at Diana's funeral).
And Mr. Bean, Rowan Atkinson, is coming too.