Surgical instruments and end effectors therefor are disclosed. In various implementations, the surgical instrument includes a surgical end effector that comprises a lower jaw and an upper jaw that are supported for movable travel toward and away from each other. The instrument may further include a firing member that is operably supported for selective operable travel within the surgical end effector. The instrument may also include a first jaw closure system that operably interfaces with the lower jaw and is configured to selectively move the lower jaw relative to the upper jaw. A second jaw closure system operably interfaces with the upper jaw and is configured to selectively move the upper jaw relative to the lower jaw. A firing system operably interfaces with the firing member and is configured to apply firing motions to the firing member to move the firing member within the end effector.