Sir Elton John has launched a campaign to promote reading and writing called the Alphabet of Illiteracy - with "A is for Aids".
Some of the world's biggest stars including Julianne Moore, Emma Watson, Usain Bolt, James Franco and Taylor Schilling, will each share a letter from the alphabet to promote International Literacy Day.
Aids campaigner Sir Elton tweeted "literacy helps stop its spread" as he highlighted how those who cannot read or write are five times less likely to understand how HIV is contracted.
The campaign is to mark the 50th International Literacy Day on September 8, raising awareness of the 758 million people worldwide who lack basic skills in reading and writing.
In the Alphabet of Illiteracy, B is for bloodshed and C is for child brides, as better education for girls leads to fewer child marriages.
The stars of film, music, politics and the arts will each adopt a letter to show how illiteracy is linked to almost every major global problem, including infant mortality, malnutrition, gender inequality and unemployment.
Project Literacy aims to ensure that by 2030, no child will be born at risk of poor literacy.
In the UK, 5.2 million adults are functionally illiterate, while one in five British children leaves primary school unable to read and write proficiently.
Model Lily Cole, who gave a speech at the House of Commons in February about the illiteracy crisis, said: "If we want to tackle many of the global challenges our world faces, we need to begin by properly addressing education and literacy."