The Subgroup on Cell and Developmental Biology brings together interdisciplinary scientists with shared and complementary interests in the mathematics of multiscale cellular dynamics. Researchers in this subgroup work on questions related to how cells make decisions in development, how gene regulatory networks influence cell fate, how internal filaments affect cell shape and intracellular dynamics, how cells interact with external signals, and how tissues and patterns form robustly during development, among many other questions. Cell and developmental biology has long proven a fertile ground for mathematical modeling and, with recent experimental advances, it is becoming an increasingly quantitative discipline. We are now able to constrain and quantify mathematical models of cellular dynamics, growing the potential for models to be used in a predictive way. The objective of this subgroup is to accelerate these efforts, encourage the interactions of researchers across disciplines and biological scales, and support the use of mathematical modeling as part of the ‘toolkit’ of cell and developmental biology.