An end effector is disclosed which comprises a shaft, an end effector rotatably connected to the shaft about an articulation joint, and an articulation driver configured to rotate the end effector about the articulation joint. The end effector further comprises a first articulation lock configured to engage the end effector and a second articulation lock configured to engage the articulation driver which co-operatively prevent the end effector from rotating relative to the shaft, when actuated. The actuation and/or de-actuation of the first articulation lock and the second articulation lock can be contemporaneous or, in certain instances, staggered.