On June 17, 2002, PNAS began daily online publication of articles at www.pnas.org. Since January 2000, PNAS articles have been published online before print on a weekly basis, in a feature called PNAS Early Edition.
The move to daily publication will increase the timesavings over print, by allowing all accepted papers to be published online immediately after final author corrections are made.
The date of online release for each article is posted on the web site and is the official publication date. Papers will be published online each business day 1–4 weeks before they appear in print. PNAS offers electronic publication in as little as 3.5 weeks after acceptance to authors who return their proofs quickly.