Robustness in organ development is the formation of the reproducible organ sizes and shapes despite perturbations in the environment, stochastic (or random) gene expression, and cellular variability. Development is remarkably robust, producing plant organs such as leaves and sepals with the same size and shape repeatedly from individual to individual. Yet, these reproducible organs are composed of cells that are highly variable in size, shape, growth, and division. My laboratory uses a computational morphodynamics approach, including genetics, live imaging, image processing, mechanical assays, and computational modeling, to elucidate the mechanisms that produce robust organ size and shape from cellular heterogeneity. We use Arabidopsis sepals as a model organ because there are four sepals on each flower; this enables statistical tests of robustness. To identify mechanisms generating robustness we have screened for variable organ size and shape (vos) mutants that disrupt the robustness of sepal morphology (Hong et al., 2016). These studies reveal mechanisms through which individual cells, which are often highly variable, collectively give rise to complex organs with reproducible and robust sizes and shapes.