An instrument assembly can comprise a shaft comprising a first drive portion of a drive system, an end effector comprising a second drive portion of the drive system, and an articulation joint rotatably connecting the end effector to the shaft. The end effector is rotatable between a first position and a second position about the articulation joint, wherein the first drive portion is not operably engaged with the second drive portion when the end effector is in the first position, and operably engaged with the second drive portion when the end effector is in the second position. The end effector can comprise a first jaw and a second jaw, wherein the first jaw is movable relative to the second jaw between an open position and a closed position within a closure plane, and wherein the end effector is rotatable within an articulation plane which is co-planar with the closure plane.