Context: Partnering with citizens and community in health research can improve health outcomes, enhance the health care system and is increasingly an expectation of Canadian granting agencies. Though the science of citizen and community engagement in research has rapidly expanded, less is known about the impact of engagement approaches on research outcomes. Rigorous approaches to evaluating participatory approaches in health research have been called for, to ensure scarce health care resources are aligned with citizen’s needs and priorities and allocated in the most impactful way. EMBOLDEN is an evidence-informed, novel community health intervention to enhance mobility that is co-designed by a 30-person Strategic Guiding Council composed of health/social service providers and older adult citizens Objectives:i) to explore how health/social service providers and older adults perceive EMBOLDEN’s engagement strategies, the engagement context and ii) to understand what is working well, and areas for improvement in EMBOLDEN’s engagement processes. Study Design: Participatory approach to developmental evaluation with a working group of 4 older adult citizen partners who are members of the EMBOLDEN project’s Strategic Guiding Council (SGC) and researchers. Setting: Community-based. Population: Community-dwelling older adults (55+). Outcome measures: Working with older adult SGC members, priorities for evaluation were identified. This group identified focus groups and questionnaire methods to capture these priorities and informed data collection tools. Results: Four older adults of EMBOLDEN’s SGC responded to a SGC-wide invitation to help design the engagement evaluation. The evaluation will prioritize capturing diversity (gender, cultural, organizations); satisfaction, fun, respect; impact of SGC input to intervention; SGC involvement across all stages of research. Findings from surveys (patient-centred evaluation tools) and focus groups will contribute to adaptations and innovations to the EMBOLDEN co-design process as the intervention is implemented in different communities. Conclusions: Older adult research partners have an important role to play in designing, implementing and evaluating co-design approaches. This project contributes to the growing field of citizen and community engagement in research by offering a participatory approach to engagement evaluation that considers diversity, satisfaction, and impact.