In 2005 we published draft guidelines for reporting studies of quality improvement interventions as the initial step in a consensus process for development of a more definitive version. The current article contains the revised version, which we refer to as SQUIRE (Standards for QUality Improvement Reporting Excellence). We describe the consensus process, which included informal feedback, formal written commentaries, input from publication guideline developers, review of the literature on the epistemology of improvement and on methods for evaluating complex social programs, and a meeting of stakeholders for critical review of the guidelines' content and wording, followed by commentary on sequential versions from an expert consultant group. Finally, we examine major differences between SQUIRE and the initial draft, and consider limitations of and unresolved questions about SQUIRE; we also describe ancillary supporting documents and alternative versions under development, and plans for dissemination, testing, and further development of SQUIRE.