Princes William and Harry Pay Tribute to Their Mother, Princess Diana

— -- Britain's Prince William and Prince Harry have made a rare tribute to their mother, the late Princess Diana of Wales.

In a foreword to a new book celebrating the fifteenth anniversary of the Diana Award, the only charity set up in her name, Diana's two sons remembered her legacy of philanthropy.

“We believe, when encouraged and supported, that young people have the ability to change society for the better,” the princes wrote in the book. "We know that our mother, in whose memory this award was established, felt the same and would be proud of its achievements to date."

The Diana Award charity was established shortly after Diana's death in a 1997 car crash in Paris to inspire and honor young people, instilling in them the belief that they have the power to change the world.

The charity has recognized more than 40,000 young people who have worked in their communities to end bullying, support mentoring programs and empowering young people to make a difference. The charity is set to celebrate its anniversary tonight at a reception at Downing Street.

“In recent years, we have both had the privilege of meeting some truly inspiring young people and those involved with the Diana Award are no exception -- working to quietly transform their communities and the lives of those around them," the princes wrote. "These young people were working hard to tackle the social issues that affected them -- such as bullying or social exclusion -- and the Diana Award empowered them to do more."

Both William, 32, and Harry, 30, are active on the charitable front themselves and have inspired many of the young people seeking to honor their late mother.

William, the Duke of Cambridge, has taken over the presidency of the Royal Marsden, of which Princess Diana was Royal Patron, and is an active supporter of Centrepoint, a charity for homeless youth, an issue on which his mother was a pioneering benefactor.

Prince Harry is Patron of the Halo Trust, the anti-mine charity that Diana supported. Prince Harry has also set up Senteable in LeSotho, which means "Forget Me Not," in memory of his mother, to raise awareness for the vulnerable children in the country devastated by AIDS and HIV.

"Over this time, the award has evolved to become a youth-driven charity that harnesses the energy and passion of young people who really are trailblazers for their generation. We believe, when encouraged and supported, that young people have the ability to change society for the better.” Princes William and Harry wrote.

Both princes have also become role models for young and old by carrying on the charitable legacy their mother established. Recently, along with William's wife, the Duchess of Cambridge, the princes established the Royal Foundation of the Duke and Duchess of Cambridge and Prince Harry. The Royal Foundation encourages and supports a broad cross section of charities focusing on young people, the armed forces and conservation.