The National Institute for Mathematical and Biological Synthesis has announced support for a working group on Spatial Cell Simulation based on a proposal by Bob Murphy and Jim Faeder, both of whom are project leaders in the National Center for Multiscale Modeling of Biological Systems. Systems biology emphasizes the creation of mathematical or computational models of biological systems such as cells and tissues, as a means both to integrate all available information and to make predictions about unmeasured mechanisms or behaviors. The working group will address critical challenges currently faced in creating mathematical/computational simulations of the inner workings and dynamics of eukaryotic cells that reflect realistic cell architecture, especially for accurately simulating changes in cell shape and organization over time. The issues to be addressed include methods for simulation that can consider dynamic cell and organelle shapes and positions and methods for learning joint probability distributions for thousands of cellular components. The working group will meet 2-3 times per year to develop new approaches to these problems, implement them in software, develop proposals for future funding of such research, and develop training materials for biomedical researchers. The first meeting will be December 1-3, 2015. Scientists interested in contributing to the effort are encouraged to contact the organizers at email@example.com and firstname.lastname@example.org.