Objective. To examine whether the theory-based social cognitions of perceived barrier frequency, barrier limitation, and self-regulatory efficacy to cope were predictors of planned physical activity among adult women with arthritis. A secondary purpose was to identify and provide a phenomenologic description of the relevant barriers and coping strategies reported by study participants. Methods. Eighty adult women (mean ؎ SD age 49.09 ؎ 12.89 years) with self-reported doctor-diagnosed arthritis participated in this observational study. Participants completed online survey measures of barriers to physical activity and, for each barrier, reported the frequency of occurrence and the extent of limitation. Measures of coping strategies for each barrier, efficacy to cope, and physical activity were also obtained. Results. A multiple hierarchical regression analysis resulted in a model that significantly predicted physical activity (F[9,70] ؍ 6.80, P < 0.01, adjusted R 2 ؍ 0.40). Barrier limitation (standardized  ؍ ؊0.56) and efficacy (standardized  ؍ 0.20) were significant independent predictors. Phenomenologic findings indicated that arthritis-specific personal barriers (e.g., pain and fatigue due to arthritis) and arthritis-specific coping strategies (e.g., activity modification) were more commonly reported than generic barriers and coping strategies. Conclusion. Self-regulatory efficacy to cope and relevant perceived physical activity barriers, which were primarily arthritis-specific and moderately or more limiting to planned physical activity, were important social cognitive predictors of physical activity, a key nonpharmacologic arthritis treatment, among women with arthritis. Future research direction should examine potential moderators of the relationship between these predictors and physical activity, such as pain acceptance.