Open Access (OA) advocates argue that PLoS ONE is now the largest scholarly journal in the world. Its parent organisation — Public Library of Science (PLoS) — was co-founded in 2001 by Nobel Laureate Harold Varmus. What does the history of PLoS tell us about the development of PLoS ONE? What does the success of PLoS ONE tell us about OA? And what does the current rush by other publishers to clone PLoS ONE tell us about the future of scholarly communication?