Adapting an Evidence-Based Physical Activity Intervention to Prevent Frailty and Functional Decline in Older Women Living with HIV - Project Summary Older women living with HIV (OWWH) experience early onset and accelerated progression of geriatric syndromes, including musculoskeletal pain, functional decline, and frailty, than the general population, placing them at heightened risk for falls, disability, loss of independence, and reduced quality of life. These aging-related conditions are compounded by multimorbidity, long-term HIV treatment effects, HIV-related stigma, and social and structural factors that limit access to and sustained engagement in evidence-based health promotion programs. Interventions that preserve physiologic reserve, maintain strength and mobility, and slow frailty progression are critical to supporting healthy aging in this growing and understudied population. Physical activity programs that combine strength training, balance, and behavior change strategies effectively improve function and reduce frailty risk among older adults; however, such programs have not been rigorously adapted or tested for OWWH whose physical and psychosocial contexts of aging differ from those of the general population. The goal of this study is to adapt and test the Fit & Strong! (F&S) evidence-based physical activity and education intervention to address HIV-specific physical, psychosocial, and contextual needs of women, aged 50 years and older, living with HIV and experiencing mobility decline. The tailored intervention will integrate group-based physical activity and behavior change strategies, fostering social support and empowerment while addressing modifiable individual-, interpersonal-, and community-level implementation determinants identified by OWWH as influencing program participation and maintenance. Using a community-engaged approach, this study will: 1) collaborate with a Community Advisory Board of OWWH to tailor the F&S program using the ADAPT-ITT model and pilot test the new intervention; 2) conduct a fully powered randomized waitlist-controlled trial with 210 participants experiencing mobility impairment to evaluate the intervention’s impact on participant health outcomes; and 3) assess implementation outcomes, including appropriateness, feasibility, fidelity, and sustainability, at the participant, instructor, and organizational levels. By targeting modifiable mechanisms of functional decline through an evidence-based group intervention, this project addresses a critical public health gap and has the potential to preserve functional independence and improve aging trajectories among women aging with HIV.