Project Summary/Abstract Multiple sclerosis is a debilitating disease usually diagnosed between the ages of 20 and 49 years with no curative options, resulting in a focus on rehabilitation strategies to manage symptoms, restore function, and improve quality of life. Physical activity, particularly exercise training, is considered one of the best rehabilitation strategies for comprehensive multiple sclerosis management. Despite strong evidence of the safety and benefits of physical activity and exercise in this population, persons with multiple sclerosis do not engage in sufficient levels of physical activity. Physical therapists are well positioned and have the expertise to facilitate physical activity and exercise participation for persons with multiple sclerosis. However, physical therapy is underutilized, particularly in people with more mild multiple sclerosis symptoms, when the best results may be achieved. A newly developed proactive physical therapy delivery model may help persons with multiple sclerosis increase and maintain their physical activity and exercise behaviors. The proposed study involves 1) a randomized controlled trial to evaluate outcomes of feasibility in the four metrics of process, resources, management, and scientific outcomes, and 2) an assessment of the immediate and sustained treatment effect of the physical therapy model compared to a waitlist control on accelerometer-measured physical activity. The feasibility trial will be conducted with a sample of 40 persons with multiple sclerosis randomized to either the intervention or waitlist control group. Participants will complete assessments at baseline, post-intervention (6 months), and follow-up (10 months). Participants will complete a summative evaluation, including surveys and one-on-one semi-structured interviews, to assess satisfaction, acceptability, feasibility, and appropriateness of the physical therapy delivery model. The proposed feasibility study, interviews, and implementation assessments will directly lead to the submission of an R01 to test the efficacy of an appropriately powered randomized controlled trial and to identify context-specific barriers and facilitators to the successful uptake of this physical therapy model in clinical settings. The dissemination of the results of this feasibility study can lead to improvements in physical therapy delivery for persons with multiple sclerosis.