Background: People with moderate-to-severe multiple sclerosis (MS) and their family caregivers do not engage in sufficient physical activity (PA) for health benefits. There is a need to develop dyadic PA interventions that target people with moderate-to-severe MS and their care-partners to the benefit of each individual and the dyad. Objectives: The objective of this study was to engage expert stakeholders in prioritizing and refining key intervention content, delivery methods, and practical/logistical aspects of a dyadic PA intervention for persons with MS and their care-partners. Methods: We used a modified e-Delphi technique comprising of two survey rounds via SurveyMonkey. Thirty-two stakeholders including healthcare providers (n=14), people living with MS (n=11), MS care-partners (n=5), and representatives of organizations that provide support services for people with MS and/or MS care-partners (n=2) participated in this study. In Round 1, participants rated items across three domains: intervention content (n=8), delivery aspects (n=9), and practical/logistical considerations (n=4), and commented on their rationale for ratings. Consensus was defined as ?70% of respondents rating the item within two points. Data were summarized and used to formulate survey Round 2. In Round 2, participants re-rated items that had failed to reach consensus, in light of experts’ comments, plus additional items generated in Round 1. We summarized participants characteristics and expertise, and group responses to each item using descriptive statistics. Open-ended comments were content analyzed. Results: Integrating survey responses and open-ended comments generated a 24-item list of recommendations for the intervention. Recommendations ranged from ensuring that content is presented in a way that emphasizes the principle that some activity is better than no activity and that encourages lifestyle activities in addition to exercise, to using videoconferencing, rather than teleconferencing as a delivery platform, to the need for flexibility in time allocation to ensure that participants needs are adequately addressed during the support calls. Conclusions: Feedback will be used to improve the quality of the intervention. The next step in this line of research will involve the evaluation of the refined intervention using a pilot feasibility randomized controlled trial design. Funding support: A. Fakolades time on this project was supported by a Post-doctoral Fellowship Award from the Multiple Sclerosis Society of Canada.