Sedentary older adults are more likely to develop physical function impairments than active older adults. Physical function measured by slow usual gait speed predicts the risk of future falls, disability, institutionalization and mortality. Behavioral physical activity interventions have improved physical activity and physical function, but have not generally been implemented where they may have the most impact -- primary care settings. In part, this is due to the limited time and training for clinical staff to screen for physical function impairment and to treat with physical activity counseling. The proposed scientific goal is to overcome these barriers by adapting an evidence-based screening tool and telephone-based physical activity intervention into primary care settings.