For many years, the Science Advisory Board (SAB) has been actively advising the Agency on the use of computer models in environmental protection. In 1989, after reviewing several models, SAB offered general advice in its first commentary or resolution (EPA-SAB-EEC-89-012), recommending that EPA establish a general model validation protocol and provide sufficient resources to test and confirm models with appropriate field and laboratory data and that an Agency-wide task group to assess and guide model use by EPA should be formed. In response, the Assistant Administrator for Research and Development (ORD) and the Assistant Administrator for Solid Waste and Emergency Response (OSWER) jointly requested the Deputy Administrator, as the chair of the former Risk Assessment Council (RAC), to establish a task force to examine the issues. The voluntary Agency Task Force on Environmental Regulatory Modeling (ATFERM) was created in March 1992 and completed a report in October 1993. In its report (EPA 500-R-94-001), the ATFERM noted that the Agency has no formal mechanism to evaluate model acceptability, which causes redundant inconsistent evaluations as well as uncertainty about acceptability of models being applied and the results that the Agency obtains with the models. The ATFERM report recommended establishment of acceptability criteria because a comprehensive set of criteria for model selection could reduce inconsistency in model selection and ease the burden on the Regions and States applying the models in their programs.