Among the different sorts of challenges for the modeling and simulation community, two types of challenges face us: challenges that optimize space and time for the computer, and challenges that improve the human interface to the modeling and simulation process itself. While of these types of challenges are important for the future health of simulation, we present a grand challenge of the latter variety, based on an area termed integrative multimodeling. The purpose of integrative multimodeling is to provide a human-computer interaction environment that allows components of different model types to be linked to one another—most notably dynamic models used in simulation to geometry models for the phenomena being modeled. We specify current modeling practices in simulation and proceed to justify a need for the challenge. We then follow this with two areas: aesthetic computing and the RUBE software framework, which supports customized “notations” for dynamic models constructed using the eXtensible Markup Language (XML).