The Duke of Cambridge is joining forces with David Beckham to launch a new campaign aimed at using the power of sport to combat illegal trade in wildlife products.
William, president of United for Wildlife, will kick off the #WhoseSideAreYouOn campaign today which will ask the next generation to chose between critically endangered species and those who kill them for money.
It is hoped the #WhoseSideAreYouOn debate will gather pace on social networking via Twitter, Facebook, Google Plus and YouTube to raise the profile of the issue.
In the run up to the launch, William and his brother Prince Harry posed side by side for a photo for United for Wildlife's Twitter account, each holding a sign bearing the start date "9th June 2014" and their own signature.
Beckham, who worked closely with the Duke on England's World Cup bid and attended his wedding, heads a team of sporting stars backing the campaign including Wimbledon champion Andy Murray, India's former batsman Rahul Dravid and retired South African rugby captain Francois Pienaar.
Last September, William and Beckham teamed up when they recorded two video campaigns against illegal wildlife products for WildAid.
Beckham said at the time: ''When I learned of the current poaching levels in Africa, I immediately agreed to help get this message out.
''It is shocking to think that we could lose these animals from the wild in our lifetimes.''
The fight against illegal wildlife trade is close to William's heart. In February, he hailed a major international conference in London on the trafficking of endangered wildlife as the '"beginning of the end of this despicable trade''.
World leaders agreed concrete steps to help safeguard endangered animals from poachers - putting their signatures to a declaration of intent.
William attended the event with Harry and their father the Prince of Wales, who gave the keynote speech, as politicians gathered to discuss how best to combat the illegal trade in rhino horn, tiger parts and elephant tusks which fuels criminal activity worth more than an estimated £11.5 billion each year.
United for Wildlife is a collaboration between seven conservation organisations and the Royal Foundation of The Duke and Duchess of Cambridge and Prince Harry.