The National Science Foundation sponsors the Geospace Environment Modeling (GEM) program, devoted to understanding the scientific underpinnings for the creation of a Geospace General Circulation Model. The GEM program is organized into finite-length campaigns, one of which is the Inner Magnetosphere/Storms (IM/S) Campaign, which is ending in 2006. The final activity of the IM/S Campaign was the IM/S Assessment Challenge (IMSAC), in which several events were selected for intense, community-wide examination. The primary purposes of the IMSAC were (1) to quantify the ability of the current set of inner magnetospheric models to predict the fields and plasma of this region during storms and (2) to codify the consensus understanding of inner magnetospheric physics. This paper introduces the reader to the IMSAC and presents a general answer to each of the IMSAC goals. In addition, highlights of the scientific advancements during the IM/S Campaign are presented for the plasmasphere, ring current, and radiation belts, along with a synthesis view of the inner magnetosphere. The biggest need for inner magnetospheric research in the near future is the continued progression toward a coupled, interconnected understanding of this region, especially the nonlinear feedback mechanisms between the plasma populations, the electric and magnetic fields, and plasma waves.