The royal brothers have set up a grant-giving foundation to help young people, wounded servicemen and women, and help sustainable development at home and abroad.
William, 27, and Harry, 25, kicked-started it with some of the money they inherited from their mother, Princess Diana, who died in August 1997. Palace sources will not say how much money they have spent initially.
They're once again following in the footsteps of their father, Prince Charles – who set up his Prince's Trust more than 30 years ago using his when he left his service in the Royal Navy.
"The Prince of Wales is pleased that his sons are beginning to develop their charitable lives," a spokesman for the heir apparent said. "It is not surprising that some of his focuses, such as young people, environment and military are reflected in some of their interests."
The Charitable Foundation of Prince William and Prince Harry has been set up "very much for the long term," a palace source tells PEOPLE. Prince William and Harry remain serving military officers but this does lay "the foundation's future official and charitable lives."
In January 2010, William is set to step up his royal duties when he undertakes a week-long tour to Australia and New Zealand. It will be his first overseas tour on behalf of his grandmother Queen Elizabeth II.