The majority of programs designed to promote physical activity in older Hispanic women includes few innovative theory-based interventions that address cultural relevant strategies. The purpose of this report is to describe the design and baseline data for Mujeres en Accion, a physical activity intervention to increase regular physical activity, and cardiovascular health outcomes among older Hispanic women. Mujeres en Accion [Women in Action for Health], a 12 month randomized controlled trial to evaluate the effectiveness of a social support physical activity intervention in midlife and older Hispanic women. This study tests an innovative intervention, Mujeres en Accion, and includes the use of a theory-driven approach to intervention, explores social support as a theoretical mediating variable, use of a Promotora model and a Community Advisory group to incorporate cultural and social approaches and resources, and use of objective measures of physical activity in Hispanic women.