The Institute of Medicine identified 3 core functions of public health: assessment, policy development, and assurance. Federal, state, and local public health agencies all have an obligation to provide these vital functions to ensure conditions in which people can be healthy. However, the few publications that provide core function applications only focus on applications at the local or state levels. The Centers for Disease Control and Prevention's Childhood Lead Poisoning Prevention Program uses a comprehensive public health approach. This article describes the Centers for Disease Control and Prevention's leading role in applying the core public health functions to prevent childhood lead poisoning.