Significant public health challenges facing the United States stem from preventable disease. The Patient Protection and Affordable Care Act dedicated substantial resources toward prevention. Among other reforms, the Affordable Care Act requires Medicaid and private health insurers to cover clinical preventive services for adults, pursuant to recommendations by the U.S. Preventive Service Task Force. This article examines the infrastructure upon which these recommendations are based, the requirements related to risk factors for leading causes of preventable disease in adults associated with tobacco and alcohol use, unhealthy diet, and inactivity, and coverage requirements for private plans and Medicaid. The article provides and assesses data comparing the health statuses of populations in and preventive services offered by states taking the Affordable Care Act Medicaid expansion versus those in states declining to expand coverage. The article suggests legislative and other methods to increase preventive clinical service requirements and notes outstanding issues for future research.