The International AIDS Society (IAS) is the world's largest association of HIV/AIDS professionals, with 11,600 members from over 170 countries as of July 2020, including clinicians, people living with HIV, service providers, policy makers and others. It aims to reduce the global impact of AIDS through collective advocacy. Founded in 1988, IAS headquarters are located in Geneva, and its president since August 2022 is Sharon Lewin.

Joseph Marie Albert "Joep" Lange was a Dutch clinical researcher specialising in HIV therapy. He served as the president of the International AIDS Society from 2002 to 2004. He was a passenger on Malaysia Airlines Flight 17, which was shot down on 17 July 2014 over Ukraine.