An Explanation and Elaboration article discusses each checklist item and gives methodological background and published examples of transparent reporting. The STROBE checklist is best used in conjunction with this article (freely available on the Web sites of PLoS Medicine at http://www.plosmedicine.org/ , Annals of Internal Medicine at http://www.annals.org/ , and Epidemiology at http://www.epidem.com/ ). Information on the STROBE Initiative is available at www.strobe-statement.org. (DOCX)