Dr. Williams recently completed a review of 35 exposure assessment models currently used and supported by the U.S. Environmental Protecton Agency. These models represent the first half of the source-to-outcome continuum and include 12 fate/transport models, 5 exposure models, and 8 integrated fate/transport and exposure models. Although most of these models were developed to assess exposures to the general public, some were developed (or can be used) to assess exposures in occupational settings. Each model is summarized with respect to its intended purpose and potential applications, level of analysis and routes of exposure, key data inputs and exposure/risk outputs, temporal and spatial resolution, treatment of variability and uncertainty, degree of model evaluation, level of internal and external peer review, and interactions with other models. This information provides a useful up-to-date resource for exposure and risk modelers and practitioners.