BackgroundTo address the challenges of the global aging population, the World Health Organization promoted age-friendly communities as a way to foster the development of active aging community initiatives. Accordingly, key components (i.e., policies, services and structures related to the communities’ physical and social environments) should be designed to be age-friendly and help all aging adults to live safely, enjoy good health and stay involved in their communities. Although age-friendly communities are believed to be a promising way to help aging Canadians lead healthy and active lives, little is known about which key components best foster positive health, social participation and health equity, and their underlying mechanisms.This study aims to better understand which and how key components of age-friendly communities best foster positive health, social participation and health equity in aging Canadians. Specifically, the research objectives are to:Describe and compare age-friendly key components of communities across CanadaIdentify key components best associated with positive health, social participation and health equity of aging adultsExplore how these key components foster positive health, social participation and health equityMethodsA mixed-method sequential explanatory design will be used. The quantitative part will involve a survey of Canadian communities and secondary analysis of cross-sectional data from the Canadian Longitudinal Study on Aging (CLSA). The survey will include an age-friendly questionnaire targeting key components in seven domains: physical environment, housing options, social environment, opportunities for participation, community supports and healthcare services, transportation options, communication and information. The CLSA is a large, national prospective study representative of the Canadian aging population designed to examine health transitions and trajectories of adults as they age. In the qualitative part, a multiple case study will be conducted in five Canadian communities performing best on positive health, social participation and health equity.DiscussionBuilding on new and existing collaborations and generating evidence from real-world interventions, the results of this project will help communities to promote age-friendly policies, services and structures which foster positive health, social participation and health equity at a population level.