BackgroundContextual factors can act as barriers or facilitators to scaling-up health care interventions, but there is limited understanding of how context and local culture can lead to differences in implementation of complex interventions with multiple stakeholder groups. This study aimed to explore and describe the nature of and differences between communities implementing Health TAPESTRY, a complex primary care intervention aiming to keep older adults healthier in their homes for longer, as it was scaled beyond its initial effectiveness trial.MethodsWe conducted a comparative case study with six communities in Ontario, Canada implementing Health TAPESTRY. We focused on differences between three key elements: interprofessional primary care teams, volunteer program coordination, and the client experience. Sources of data included semi-structured focus groups and interviews. Data were analyzed through the steps of thematic analysis. We then created matrices in NVivo by splitting the qualitative data by community and comparing across the key elements of the Health TAPESTRY intervention.ResultsOverall 135 people participated (39 clients, 8 clinical managers, 59 health providers, 6 volunteer coordinators, and 23 volunteers). The six communities had differences in size and composition of both their primary care practices and communities, and how the volunteer program and Health TAPESTRY were implemented. Distinctions between communities relating to the work of the interprofessional teams included characteristics of the huddle lead, involvement of physicians and the volunteer coordinator, and clarity of providers’ role with Health TAPESTRY. Key differences between communities relating to volunteer program coordination included the relationship between the volunteers and primary care practices, volunteer coordinator characteristics, volunteer training, and connections with the community. Differences regarding the client experience between communities included differing approaches used in implementation, such as recruitment methods.ConclusionsAlthough all six communities had the same key program elements, implementation differed community-by-community. Key aspects that seemed to lead to differences across categories included the size and spread of communities, size of primary care practices, and linkages between program elements. We suggest future programs engaging stakeholders from the beginning and provide clear roles; target the most appropriate clients; and consider the size of communities and practices in implementation.Trial registrationClinicalTrials.gov: NCT03397836.