Kate will also be the first future queen to have graduated from college and lived with the future king before marriage.
Not much is known about the woman, whose life has been compared to Princess Diana's, William's mother, in every way. And undoubtedly, this modern young woman will have to endure this comparison for life.
Kate, 28, met Prince William, also 28, while they were students at the University of St. Andrews in Scotland in 2001. The two roomed on the same floor in the school's dorm and in 2002 moved off campus to a private house with two close friends. The couple has been together for seven years.
Unlike Hollywood starlets, who can't help but get caught in inappropriate situations, Kate has never been seen in a compromising position. She has never given an interview to the press or been caught stumbling out of a nightclub, and, in fact, she has been known to refresh her makeup before leaving a club in the middle of the night.
But the road to wedded bliss hasn't always been romance and roses. The couple separated in 2007 and reports surfaced that Kate's mother had offended the Queen by using the word "toilet" instead of "lavatory." Supposedly, Prince William was horrified when he heard these rumors and called Kate and her mother to apologize for the attacks on her character.
The couple got back together soon after, and engagement rumors have persisted ever since.
Her Family and Early Schooling
Kate's father, Michael, was an airline pilot who met Kate's mother, Carole, when she worked as a flight attendant. They married in 1980. In 1987, they opened Party Pieces, a direct-mail party-supply company.
Through the success of Party Pieces, Mr. and Mrs. Middleton were able to send their three children (Kate has two younger siblings, Pippa and James) to Britain's top schools. Kate attended Marlborough, one of England's most elite institutions, where fellow students come from aristocratic and royal families.
While in school, Kate was nicknamed "Princess-in-Waiting" by her classmates because she never misbehaved. She didn't smoke or drink, and didn't date often.
The future princess was popular in school and had a self-deprecating sense of humor, saying once, "I'm a bit thick."
Kate is also the first royal bride to model lingerie. William's future bride was wearing a sheer dress with black underwear. At the Don't Walk charity fashion show in March 2002, Prince William was overheard telling his friend Fergus Boyd, "Wow, Fergus, Kate's hot!"
After the show the two spent a few minutes alone at a party and toasted Kate's success. The two were talking and a friend who witnessed the encounter recalls, "There was definitely chemistry between them and Kate had really made an impression on William, but she played it very cool. She didn't want to give off the wrong impression or make it too easy for him."
Her Career, or Lack Thereof
Unlike her late mother-in-law, Princess Diana, Kate has not held a steady job since graduating from college in 2007. Dubbed by the British tabloids as "Waity Katie" for her aversion to work, Kate has taken on a number of jobs that she held for only a short time.
After graduation, Kate was hired as an accessory buyer at the British chain Jigsaw, but lasted less than a year. She took the job with the stipulation that she could leave whenever she wanted, for however long she wanted, whenever Prince William called. She has since held a job at her parents' party-supply company.
Royal aides have said that the Queen is concerned that the future princess doesn't have a full-time job and has suggested that charity work fill her time to offset a negative public perception.
An aide told the Daily Mail, "The Queen has made it known that she feels Kate should get involved with a charity, possibly an animal charity, where she can be seen to be doing something proactive and something entirely safe. It is important that Kate isn't seen to be doing anything controversial, and she needs to do something completely different from any of the charity work that Diana did."
The Sunday Telegraph reported recently that a royal insider confirmed that Kate was scheduled to attend several charity events prior to the wedding announcement, adding: "She will take a higher profile before the engagement is announced."
Will She Fit In?
Claudia Joseph, who authored Kate's biography, Kate: Kate Middleton: Princess in Waiting, in 2009, has said of Kate's upbringing: "Kate has been brought up to eat with the right knife and fork." She added that all Buckingham Palace wants in a prospective spouse is 'etiquette and style.' I don't think it's about the right background."
The world assumed that the royal family approved of the match when the couple was spotted kissing in public while on vacation with Prince William's father, Prince Charles, and brother, Prince Harry.
The term "commoner," which has been used to describe the future princess, simply means that she has no relatives or any connection to nobility or royalty. The last time a future British king married a commoner was in 1660 when the future King James II secretly wed Anne Hyde in the middle of the night. The country was outraged, but the future Queen Anne gave birth to two queens subsequently, Mary and Anne.
Today, royals across the world are not so concerned with the ancestry of a royal spouse. Crown Prince Felipe of Spain married a former journalist in 2004 and Swedish Crown Princess Victoria, who is heir to the throne, surprised people with her announcement of her engagement to a fitness trainer.
"William's not doing anything unique by choosing a commoner," says Marilyn Braun, who writes the blog The Kate Middleton Report. "It's about who he loves, and that's that. People are rooting for him to be happy, especially after Charles and Diana's marriage."
The Diana Factor
After the world watched the fairy-tale wedding of Prince Charles to Lady Diana in 1981 that imploded in the 1990s, royal watchers agree that the royal family has shifted its attitudes as to who would make a good spouse for the future king of England.
Lady Diana was a 20-year-old kindergarten teacher with a blueblood past, a virgin who seemed to know her place when she got engaged to Prince Charles, who was 32 at the time. Looking back at video footage of the engaged couple, it's obvious that she was in love with her prince, while Charles was not in love with her. He was in love with Camilla Parker Bowles, his current wife, whom the palace deemed an unsuitable wife for the future king in the 1970s.
Royal watchers have assumed that Prince William's parents' divorce in 1996 accounts for his reluctance to say "I do" at a young age. He once said in an interview that he thinks 28 is a good age to get married. He turned 28 on June 21.
Kate Middleton is sure to garner the same attention Princess Diana did when she became Her Royal Highness Princess Charles of Wales (royal women take their husband's full title), and some are speculating that the marriage will increase the popularity of the royal family, which has been in decline since the untimely death of Princess Diana in 1997.
While William waits to become king of England, which may not happen until he is in his fifties -- most royal experts believe that Prince Charles still wants the "top job," as it is called. Kate will become Queen Catherine when William is crowned king.
Browse our gallery of Royal Weddings from Queen Victoria to Prince William
Visit RoyalWedding.aol.com for the Most Comprehensive Royal Wedding Coverage on the Web