Computer models are important tools for assessing regional carbon sequestration and other environmental impacts of agricultural management practices. The Environmental Policy Integrated Climate (EPIC) model is a very flexible model that has been used to make a wide range of field- and regional-scale environmental assessments. Large regional-scale applications of EPIC and similar models can require thousands of runs, resulting in a huge data management task. To address this problem, the Center for Agricultural and Rural Development (CARD) has developed an interactive EPIC (i_EPIC) software package that provides an automated approach to executing large sets of EPIC simulations. Overviews of both the latest EPIC version and the i_EPIC software package are presented. We also present examples of regional applications using both EPIC and i_EPIC conducted by the Resource and Environmental Policy Division of CARD, by the Joint Global Change Research Institute of the University of Maryland and the Pacific Northwest National Laboratory, and by the Resource Assessment Division of the Natural Resources Conservation Service, U.S. Department of Agriculture.