CONTEXT: Historically, public health professionals lacked the capacity to evaluate and conduct key investigations into the health of their environment. By bringing together environmental and health effects data from a variety of data sources, the National Environmental Public Health Tracking Network (Tracking) allows users to easily analyze and research the relationships between human health and the environment. OBJECTIVE: As the Tracking Network has matured, its information has been used to guide public health actions, generate hypothesis, and demonstrate relationships between environment and health outcomes. PARTICIPANTS: The Tracking Network is composed of state, local, and national environment and public health partners. SETTINGS: The Environmental Public Health Tracking Network is part of the National Center for Environmental Health at the Centers for Disease Control and Prevention. DESIGN: Tracking standardizes existing data from diverse sources while leveraging technologies and applying sound communication practices to provide a user-friendly interface for the data system by all types of users.