Public Library of Science

The Public Library of Science began in 2000 with an online petition initiative by Nobel Prize winner Harold E. Varmus, formerly director of the National Institutes of Health (NIH) and at that time director of Memorial Sloan–Kettering Cancer Center; Patrick O. Brown, a biochemist at Stanford University; and Michael Eisen, a computational biologist at the University of California, Berkeley, and the Lawrence Berkeley National Laboratory. The petition called for all scientists to pledge that, from September 2001, they would discontinue submission of articles to journals that did not make the full text of their articles available to all, free and unfettered, either immediately or after a delay of no more than six months. Although tens of thousands signed the petition, most did not act upon its terms; and in August 2001, Brown and Eisen announced that they would start their own nonprofit publishing operation. In December 2002, the Gordon and Betty Moore Foundation awarded PLOS a $9 million grant, which it followed in May 2006 with a $1 million grant to help PLOS achieve financial sustainability and launch new free-access biomedical journals.

The PLOS organizers turned their attention to starting their own journal along the lines of the UK-based BioMed Central, which has been publishing open-access scientific articles in the biological sciences in journals such as Genome Biology since 2000. The PLOS journals are what is described as "open-access content"; all content is published under the Creative Commons "attribution" license. The project states (quoting the Budapest Open Access Initiative) that: "The only constraint on reproduction and distribution, and the only role for copyright in this domain, should be to give authors control over the integrity of their work and the right to be properly acknowledged and cited."

As a publishing company, the Public Library of Science officially launched its operation on October 13, 2003, with the publication of a print and online scientific journal entitled PLOS Biology, and has since launched 11 more journals. One, PLOS Clinical Trials, has since been merged into PLOS ONE. Following the merger, the company started the PLOS Hub for Clinical Trials to collect journal articles published in any PLOS journal that related to clinical trials; the hub was discontinued in July 2013.

PLOS became a signatory of the SDG Publishers Compact in 2023, and has taken steps to support the achievement of the Sustainable Development Goals (SDGs). These include the introduction of five new open-access journals in 2021 to publish research relevant to the SDGs: PLOS Climate, PLOS Water, PLOS Sustainability and Transformation, PLOS Digital Health, and PLOS Global Public Health.

In 2011, the Public Library of Science became an official financial supporting organization of Healthcare Information For All by 2015, a global initiative that advocates unrestricted access to medical knowledge, sponsoring the first HIFA2015 Webinar in 2012.

In 2012, the organization quit using the stylization "PLoS" to identify itself and began using only "PLOS".

In 2016, PLOS confirmed that its chief executive officer, Elizabeth Marincola, would be leaving for personal and professional reasons at the end of that year. In May 2017, PLOS announced that their new CEO would be Alison Mudditt with effect from June.

In 2021, PLOS announced a policy that required changes in reporting for researchers working in other countries as an attempt to address neo-colonial parachute research practices.