Marshfield Clinic is a not-for-profit, physician-governed multispecialty group practice serving residents of rural Wisconsin through a regional ambulatory care system, an affiliated health plan, and related foundations supporting health research and education. Marshfield has engaged its physicians and staff in a program of clinical performance improvement aimed at enhancing patient access, coordination of care, and efficiency of clinical operations. An internally developed electronic health record acts as a care planning tool for delivering preventive care and managing chronic diseases. A telemedicine network expands access to care for patients living in rural and remote areas. Marshfield Clinic’s experience shows how an organized group of physicians can improve patient outcomes and reduce costs by undertaking a population-based approach to ambulatory care management supported by robust information technology. It also suggests that group-level performance incentives that are aligned with an organization's strategic goals have the potential to enhance population health management.