Population health refers to the concept of providing care for an entire population of patients, either through a public health entity, a practice, or an insurance plan. Examples of global population health programs include efforts to increase HIV-AIDS screening, vaccination for COVID-19, initiatives to reduce air pollution, plans to ensure clean and safe water, and efforts to reduce cardiovascular risk factors, such as smoking cessation, weight loss, or choosing healthy foods for large populations of patients. Successful population health programs require coordination among healthcare practitioners, the community, and payers. This chapter describes the four pillars of population health: chronic care management, quality and safety, public health, and health policy. This chapter further discusses a major facet of population health by reducing emergency room visits, as well as ensuring access to lower-cost facilities such as doctor’s offices and urgent care centers, which leads to decreased costs and increased efficiency in care delivery.