Managed care will present many new challenges to health care providers in their efforts to improve the quality of the preventive care their patients receive. Managed care will present both formidable obstacles to prevention and previously unknown opportunities to enhance population-based preventive services. Whether these opportunities are realized depends on the degree and quality of the involvement of health care providers in managed care institutions. Provider and public health input is particularly needed to promote the development of uniform preventive care standards, the development of information systems for continuous monitoring of preventive service delivery, and to enhance clinic-based preventive efforts, and the development of reimbursement mechanisms that provide incentives for prevention. Independent research and oversight is needed to show the impact of various types of managed care on preventive service delivery and quality of care. The effects of managed care on the preventive care that patients receive will ultimately be determined by the quality, priorities, and determination of the management.