Although the tools available to ecological risk assessors have become more sophisticated, the basic questions remain the same. Foremost among those questions is what spatial scale is appropriate from an ecological, toxicological, operational and regulatory perspective for the ecological risk assessment. Once a spatial scale has been defined, the risk assessor needs useful modeling tools with enough power to evaluate exposure at the selected spatial scale and models that include a consideration of not only the physical size of an assessment area, but also the habitat suitability with respect to the needs of a number of wildlife species. To address this need, our team developed a spatially explicit exposure module (SEEM) for the U.S. Army that considers these aspects for some terrestrial wildlife species. SEEM offers the risk assessor the opportunity to improve the ecological relevance of the risk assessment by considering spatial aspects of exposure through an evaluation of heterogeneous habitat use and chemical patterns and a comparison of exposure with the potential for toxicological effects, resulting in a population measure of risk. SEEM predicts and compiles exposures for all individuals within a local population, rather than a single representative individual. In addition, SEEM increases the predictive capabilities of the exposure assessment by incorporating habitat preferences in the determination of daily exposure estimates. The model will track an individual over an ecologically-relevant period of time as it travels across a landscape. The individual will move according to a set of predetermined rules and exposure for a population of individuals will be tracked over time. The module is being developed for inclusion within the U.S. Army Risk Assessment Modeling System (ARAMS).