On the 15th and 16th November 2018, the Core Outcome Measures in Effectiveness Trials (COMET) Initiative held its seventh international meeting. After success at COMET VI, the COMET meeting returned to De Rode Hoed (The Red Hat) in Amsterdam for their second consecutive meeting. One-hundred and fifteen participants gathered from around the world, coming from five continents and 18 countries. COMET was awarded an MRC HTMR Impact Award to support the attendance of and participation of several researchers from low- and middle-income countries (LMIC) at COMET VII. Four participants successfully joined COMET VII, which included researchers from Brazil, India, and two different regions of Africa. COMET will work with these LMIC partners to develop a COMET strategy for further supporting the development, dissemination, and use of core outcome sets (COS) in LMICs. COMET VII consisted of a day and a half of plenary talks, contributed presentations, and workshops. Throughout the meeting, 45 posters created an opportunity for networking and stimulated discussion across a range of topics including (but not limited to): COS across the healthcare system, how to decide on the scope of a COS, how to measure outcomes in a COS, patient and public involvement and participation in COS, and COS uptake and implementation. These topics echoed the overall themes of the program, and speakers’ presentations can be viewed at http://www.comet-initiative.org/events/pastcomet. As in previous meetings, patient participation and involvement in COS development was a key feature of COMET VII. Along with a patient-focused workshop, there was a dedicated session that included an update from Rosemary Humphreys and Heather Bagley from the COMET People and Patient Participation Involvement and Engagement Working Group. They highlighted new resources including a video explaining what a COS is (http://www.comet-initiative.org/resources/PlainLanguageSummary), tips for designing an accessible COS consensus meeting, and research ethics considerations for COS studies with patients. All of these resources and more can be found at http://www.comet-initiative.org/ppi. The program was also interspersed with contributed talks that focused on patient participation, including methods for large international patient and public participation (Astrid Chevance, METHODS team, Center for Research in Epidemiology and Statistics, Paris) and a case study from the GRAPPA-OMERACT working group that described including patients in the process of outcome measurement tool selection (Maarten de Wit, OMERACT). Lucy Brading (University of Liverpool) presented thought-provoking results of interviews with COS patient research partners, as well as an ethnography study including 48 hours of observation. Results included a blurring of patient research partner and patient participant roles as well as developers’ aspirations to find the "right" patient research partner, often deemed to be a patient with previous PPI experience. Although PPI partners and researchers face distinctive challenges in their partnership to develop a COS, there is overriding opinion that their contribution is impactful. There is a current interest in identifying how COS might fit into the different stages of the healthcare research system. COMET VII provided a platform for relevant initiatives to start having a conversation about how they can support COS in and through the healthcare research system. The second session on day one focused on how different groups can influence and increase COS uptake reflecting the perspectives of Health Technology Assessment (HTA) agencies, clinical guideline developers, and trial/health research funders. With their proximity to reimbursement/coverage decisions, HTA bodies can increase awareness of COS, encourage COS development, and support uptake of COS. Relevant bodies have identified the potential challenge of different organizations’ requirements for condition-specific versus generic quality of life outcomes in COS. The second day of COMET VII started with a panel session with representatives of five relevant global initiatives: OMERACT (Peter Tugwell), CS-COUSIN (Jochen Schmitt), Sean Tunis (CMTP), ICHOM (Christina Akerman), and Robby Nieuwlaat (GRADE). This session stimulated discussion about the overlap and differences between these different initiatives. Although Sean Tunis described this group of representatives as a “smorgasbord of initiatives,” there was a clear willingness to keep communication open and work together in the future. COS may serve as a thread that pulls all the way through the healthcare research ecosystem, thus COMET VII was the ideal platform to initiate these discussions with relevant groups and individuals. Funding for the publication of the COMET VII conference proceedings was provided by the Journal of Evidence-based Medicine. Doug Altman (1948–2018), a founding member of COMET, passed away on Sunday 3 June 2018. Doug was brilliant, witty and generous. His family, friends, and many colleagues around the world will sorely miss him. It was an honor to have Doug on board the COMET Initiative and his work will long continue to inspire. Doug was remembered in a special session, led by Jamie Kirkham (University of Liverpool), at COMET VII.