The objective is to develop a new computational model of the large- scale dynamics of the Earth's magnetosphere by merging two existing models: (i) the global 3d MHD code that was orginially developed at the Naval Research Laboratory, and (ii) the Rice Convection Model (RCM). The merged code will retain the self-consistency and comprehensiveness of the MHD code and will include the bow shock, magnetosheath, solar-wind/magnetosphere interactions, as well as the distant tail. But the merged code will also utilize the Rice Convection Model's finely gridded, many-fluid representation of the inner magnetosphere and near-Earth plasma sheet. In addition, the RCM's representation of the magnetospheric interior will be substanitally improved through the use of the self-consistent time- dependent magnetic field supplied by the MHD model. Merger of the two codes will be accomplished in three phases, with careful testing and analysis at each step. In each phase, the code will be used to simulate specific, well-observed magnetospheric events, and simulation results will be tested against observations obtained in GEM campaigns.