Prince William penned an emotional letter on his mother, Princess Diana‘s, birthday to recognize recipients of an award named her honor.

Each year, the prestigious Diana Award is presented to select young people ages 9-25 to honor their humanitarian work and social action, per People. On Friday (July 1), 180 people from 29 countries, including 20 winners from the U.S., will be recognized during a virtual ceremony. To pay tribute to the 2022 recipients, the Duke of Cambridge penned a letter acknowledging how their work continues his mother’s legacy.