This workshop on modeling cells and cell communities addresses technical challenges characteristic of complex and modular cell models. The presentations will describe whole-cell models encompassing metabolism, protein expression, and other cellular subsystems, as well as multi-cell models describing tissues or microbial communities. In the practical part of the workshop, we explored automated model construction, submodel coupling, and possible uses of SBML in setting up heterogeneous cell models. In particular, we discussed the usage of the SBML “comp” package to couple dynamic and stoichiometric models, and novel XML and SBML file formats for Resource Balance Analysis models.