An impact factor of 13.9 places PLoS Biology above such established journals as EMBO Journal, Current Biology, and the Proceedings of the National Academy of Sciences. In fact, in ISI's category of general biology journals, PLoS Biology is ranked number 1.
PLoS Biology was launched in October 2003, as an open-access home to the very best in biological research. By any measure, the impact of this launch was impressive. The on-line publication of the first issue was accompanied by strong and favorable media coverage, and subsequent issues continue to receive regular attention. Content from PLoS Biology has been read, copied, redistributed, and reused, without restriction (aside from proper citation of the authors), and now we know that the journal has also been cited time and time again.
PLoS Biology was launched to provide biologists who support open access a high profile journal for their best research papers and to demonstrate that open-access publishing works for a selective journal that only publishes outstanding science. Thanks to support from funding agencies, librarians, open-access advocates, and the scientific community ?in particular, the editorial board members of PLoS Biology, the reviewers, and most of all the authors who have submitted excellent work to a fledgling journal ?a substantial step has been taken toward these goals.
But there is still a long way to go before the mission of the Public Library of Science ?to make the world's treasury of scientific and medical literature a public resource ?is fulfilled. We hope that PLoS Biology's first imp act factor will inspire even greater support for PLoS journals and for open access.
* Thomson ISI calculated the impact factors that it announced this year by counting all the citations in 2004 to content that appeared in 2002 and 2003 and then dividing that number by the number of articles published in 2002 and 2003. For a long-standing journal, therefore, this number reflects the mean (average) number of citations over the course of a year to articles published over the two prior years. For PLoS Biology, this number refers only to articles published in its first three issues in the fall of 2003, which is why the initial impact factor is considered preliminary.