Currently there i s a lack of consistency in outcomes measured across studies evaluating nonpharmacological health and social care community-based interventions for people living with dementia, which obstructs comparisons for effectiveness and makes the interpretation of results and meta analysis difficult. One way to address this is to use and report a core outcome set—a list of core outcomes that should be measured and reported as a minimum across all relevant effectiveness trials. In phase 1, outcomes were extracted from existing trials (n = 124) and key stakeholders (people living with dementia, care partners, and health and social care professionals; policymakers and researchers) were recruited to interviews and focus groups (n = 55) in order to identify important outcomes. On the back of unsuccessful attempts elsewhere at involving people living with dementia in a Delphi survey, in phase 2 the research team facilitated substantial involvement of people living with dementia as co-researchers in order to design a modified, accessible, and innovative two-round Delphi survey method. Across the stakeholder groups, the excellent response rate in the Delphi (86.3% response rate between rounds—R1 n = 285; R2 n = 246) reflects the substantive work undertaken to ensure the method was accessible to people living with dementia. The final core outcome set was ratified at a consensus meeting (again, modified to accommodate people living with dementia), where 13 outcomes were finalized as core. The next phase of the study will undertake a systematic review to assess how outcomes should be
measured.