The U.S. Environmental Protection Agency’s (EPA) Office of Research and Development (ORD), National Center for Environmental Assessment (NCEA) recently released an on-line toolbox for exposure and risk assessors, called EPA EXPOsure toolBOX or EPA-Expo-Box. It is laid out as a series of “Tool Sets” that will guide users through the exposure assessment process from multiple perspectives. The Tool Sets include: Exposure Assessment Approaches, Media, Exposure Routes, Potentially Exposed Populations, Tiers and Types of Exposure Assessment, and Chemical Classes. Each Tool Set provides annotated links to databases, models, guidance documents, and reference materials (i.e., ‘tools’) which will be useful to scientists involved in human exposure assessment. Included is a search interface that... allows users to identify relevant tools using key words or topics. This paper highlights some of the unique features of the toolbox. EPA-Expo-Box is available at: http://www.epa.gov/risk/expobox.