Presented at the Eighth International Congress on Peer Review and Scientific Publication (September 10–12, 2017; Chicago, USA) Abstract Objective: The Guidance for Developers of Health Research Reporting Guidelines recommend multidisciplinary stakeholder involvement, transparent and complete reporting, and updating guidelines based on feedback. Developers are accountable for stakeholder engagement, but how broad and meaningful is such engagement? Our objective was to provide empirical feedback to developers by investigating (1) the involvement of those ultimately affected by guidelines (eg, patients and carers) and regular end users of guidelines (eg, publication professionals), and (2) the transparency and completeness of reporting stakeholder involvement. Design: For this prospective study, conducted from September 2016 to January 2017, we included every reporting guideline for the main study types, as listed on the EQUATOR Network website. We pilot-tested a standardized data collection spreadsheet to extract data from the corresponding guideline publications. We quantified patient, carer, and publication professional involvement and used statisticians (listed as stakeholders in the Guidelines) as a control group. We assessed reporting transparency and completeness using the AGREE Reporting Checklist for documenting stakeholder involvement. For qualitative insights, we interviewed leaders from nonprofit, international, patient advocacy (International Alliance of Patients’ Organizations [IAPO]) and publication professional (Global Alliance of Publication Professionals [GAPP]) organizations. Results: Of the 33 guideline publications, the mean (SD) number of authors was 9 (SD 5.7, min 3, max 30) (median, 7; IQR, 5-11) and the mean (SD) number of working group members was 45 (SD 38.4, min 5, max 147) (median, 30; IQR, 23-43). Statisticians were authors for 24% (8/33) of the publications and were working group members for 15% (5/33). Patients, carers, and publication professionals were rarely identified, either as authors (0, 0, and 0, respectively) or working group members (0, 1 [3%], and 0, respectively). Reporting stakeholder involvement was deficient (eg, for statistician involvement, only 25% of publications met AGREE Recommendations). Leaders from IAPO and GAPP were not aware of having been invited to participate in developing guidelines, but thought that their stakeholders could provide unique and important insights. They encourage guideline developers to contact them to facilitate meaningful involvement. Conclusions: Guideline developers have rarely involved stakeholders affected by guidelines (patients, carers) or those regularly using guidelines (publication professionals) in the development process. The involvement of these key stakeholders could enhance the credibility, dissemination, and use of guidelines. If patients, carers, and publication professionals were represented by other stakeholders (which is not ideal given potential conflicts of interest), this was not documented; readers do not know who represented whom. The transparency and completeness of reporting of stakeholder involvement should be improved. Transparency and Completeness in the Reporting of Stakeholder Involvement in the Development and Reporting of Research Reporting Guidelines Karen L. Woolley PhD CMPP,1-3 Serina Stretton PhD CMPP,4 Lauri Arnstein MBBS5 1ProScribe KK Envision Pharma Group, Tokyo, Japan; 2University of Queensland, Brisbane, Queensland, Australia; 3University of the Sunshine Coast, Maroochydore DC, Queensland, Australia (karen.woolley@envisionpharmagroup.com); 4ProScribe Envision Pharma Group, Sydney, New South Wales, Australia; 5Evidence Envision Pharma Group, London, UK Acknowledgments and disclosures • No external funds were used for this research study. All authors are employees and shareholders of Envision Pharma Group and members of not-for-profit associations supporting ethical publication practices. KLW is a shareholder of