The shape of animal cells is primarily determined by the cellular cortex, a cross-linked network of actin and myosin lying directly beneath the plasma membrane. Although it is increasingly clear that the study of cell mechanics is essential to understand cellular morphogenesis, the physical properties of the cortex are poorly understood. Our previous study on the mechanics of cytokinesis identified cortex tension, network turnover and cellular elasticity as key mechanical parameters controlling cell morphology. A physical description coupling cortex mechanics to cellular shape changes indicates that modulation of these three key parameters could be sufficient to induce a variety of morphological behaviors, including symmetric ingression of a contractile ring, cortex oscillations, and even asymmetric cell cleavage. The aim of this proposal is to reveal the intrinsic shape-generating potential of the cortex and to understand how this potential is used and controlled during cell division. To do so, we will first investigate how cortex tension, turnover and cell elasticity are controlled throughout division. We will test our understanding of cell shape mechanics by exploring how perturbing these properties affects the shape of the dividing cell. We will then explore whether cortical contractions can lead to asymmetric cytokinesis by attempting to induce differences in size between daughter cells by mechanical perturbations. Finally, we will use blebs separated from cells as model isolated cortices and investigate the control of shape dynamics in this simplified system. Our interdisciplinary approach will produce an integrated description of the mechanical function of the cortex in cell shape changes. More generally, I expect that this work will unveil some of the fundamental principles of cell morphogenesis by resolving how the coordinated regulation of a single set of physical parameters can unify seemingly disparate cellular morphogenetic events.