Former President Bill Clinton and Microsoft Chairman Bill Gates are the main attraction at this year's AIDS conference in Toronto, where experts are meeting to discuss ways to combat the disease.
Together, the two leaders have brought a profound change to the way AIDS is fought.
"Bill Gates and Bill Clinton are saying things no one else has said, and doing things no one else has done," said UCLA AIDS Institute professor Thomas Coates.
Gates is offering two contributions: a $2 billion pledge for AIDS initiatives, and an unprecedented focus on preventing the disease.
"Every case you stop today, it stops literally dozens of cases later," Gates said.
The billionaire is funding research not only for an AIDS vaccine, which may be decades away, but for more immediate, controversial strategies.
Gates is encouraging the use of condoms, testing gels and creams women can use to block infection. He is also setting up needle exchange programs for drug users.
"Bill Gates is the engine of prevention research right now," Coates said.
Adding to those efforts is former President Bill Clinton, who is using his connections to help underdeveloped countries buy AIDS drugs cheaply and deliver them more efficiently so that millions of more patients may be treated.
"He is purchasing drugs at a very cheap price by negotiating with companies. He buys them in large numbers from many different countries at the same time," said Dr. Michael Merson at the Yale School of Public Health.
Clinton said he has secured prices to bring the first round of drugs to patients for as low as $120 per person for a year, roughly 1 percent of what AIDS treatments cost in the United States.
Together, the two "Bills" are on a bold crusade that is already saving lives.