From PEOPLE Magazine Click to enlarge
Though Prince William and Prince Harry were too young to have a say in their mother's 1997 funeral, they took great care in planning her memorial. For nine months, William, 25, and Harry, 23, discussed the guest list, sought out appropriate readings and tested music on their iPods before choosing hymns like "I Vow to Thee My Country," a favorite of their mom's.

And, in the emotional hour-long service on Aug. 31 at the Guards' Chapel in London, Prince Harry celebrated his mother's memory in a speech he had written himself, drawing tears and applause from the crowd gathered outside. "We both think of her every day, we speak about her and laugh together at the memories," said Harry, speaking for himself and Prince William, who read a somber Bible passage at the service. "Her beaming smile greeted us from school. She kissed us last thing at night. She was, quite simply, the best mother in the world. We miss her."

The 500 guests included Prince Charles and Diana intimates such as Sir Elton John and photographer Mario Testino. Noticeably absent were William and Harry's girlfriends, Kate Middleton and Chelsy Davy, who weren't invited, and the princes' stepmother, Camilla, Duchess of Cornwall, who initially accepted their invitation but eventually bowed out. ("My attendance could divert attention from the purpose of the occasion," she explained in a statement.)

The newfound maturity Harry displayed at the occasion impressed guests. Although he admitted during a rehearsal to being "really nervous," the prince was poised and at ease before the crowd. "He wanted to say something about his mother," said a friend. "From a bit of a lost soul, Harry is turning into a special young man." A young man who, alongside his brother, "did incredibly well" at the memorial, says another source. "Diana would have been proud."