The findings described in this supplement can help improve collaboration among public health and other stakeholders who influence population health, including employers, health plans, health professionals, and voluntary associations, to increase the use of a set of clinical preventive services that, with improved use, can substantially reduce morbidity and mortality in the U.S. adult population. This supplement highlighted that the use of the clinical preventive services in the U.S. adult population is not optimal and is quite variable, ranging from approximately 10% to 85%, depending on the particular service. Use was particularly low for tobacco cessation, aspirin use to reduce risk of cardiovascular disease, and influenza vaccination; however, ample opportunity exists to improve use of all of these services. Among the specific populations least likely to have used the recommended services, persons with no insurance, no usual source of care, or no recent use of the health-care system (if included in the analysis) were the groups least likely to have used the services. Use among the uninsured was generally 10 to 30 percentage points below the general population averages, suggesting that improvements in insurance coverage are likely to increase use of these clinical preventive services. A randomized, controlled trial of an expansion of Medicaid coverage by Oregon in 2008 supports this hypothesis by demonstrating improved use of clinical services with increased health insurance coverage. A recent survey among the uninsured found a low level of awareness of the provisions of the Patient Protection and Affordable Care Act of 2010 as amended by the Healthcare and Education Reconciliation Act of 2010 (referred to collectively as the Affordable Care Act [ACA]). Therefore, improving opportunities for coverage might be insufficient, and focused efforts by governmental health agencies and other stakeholders are likely to be needed to enroll uninsured persons in health plans. In addition, although use of the preventive services in insured populations was greater than among the uninsured, use among the insured was generally <75%, and often much less. Therefore, having health insurance coverage might not itself be sufficient to optimize use of clinical preventive services, and additional measures to improve use are likely to be necessary.