A bio-chemo-mechanical model is described that targets contractility, adhesion, signaling, and cytoskeleton formation and remodeling, where the effort in the case of the last phenomena is focused on actomyosin stress-fibers. The contractility of the cell is driven by the stress-fibers, which also determine much of the active and passive mechanics that characterize the cell’s mechanical behavior. The stress-fibers attach to adhesion proteins that connect the cell to an extracellular matrix or to a substrate, and apply contractile force through them. This in turn generates signals that can trigger cytoskeleton formation and remodeling. The signals can also arise from external sources such as nervous impulses and biochemical changes to the cell’s surroundings. The model is installed as a user element in a finite element code and used to simulate cell behavior in vitro, such as contraction on a compliant, smooth, flat substrate, or on a bed of compliant posts. Interactions with patterned substrates are also modeled, such as where cells have a limited area to which they can adhere, or where the cells interact with grooves. The results of these simulations are very encouraging as they are largely consistent with observed cell behavior.