A bimodal prosthetic ankle-foot system has been developed to support the demands of both walking mobility and standing balance. Using a novel hydraulic locking mechanism, this system provides a curved effective rocker shape for walking and a flat effective rocker shape for standing and swaying on non-level surfaces. To date, the hydraulic cylinder sub-assembly has been cycle tested to 1.2 million cycles. Future testing with lower-limb prosthesis users is planned, which will reveal the extent to which this new hydraulic ankle-foot design improves standing balance on both level and non-level surfaces. The capacity for an automatic switching algorithm, designed to appropriately detect and switch between modes as users transition between walking and standing tasks, will also be evaluated.