A surgical stapling instrument, comprising: a rotary input shaft; means for selectively applying rotary input motions to said rotary input shaft; a surgical end effector, comprising: a first jaw that comprises a surgical staple cartridge; a second jaw comprising an anvil and selectively movable relative to said first jaw between an open and closed position; a firing shaft operably interfacing with said rotary input shaft such that said firing shaft rotates in response to rotation of said rotary input shaft; a firing member in threaded engagement with said firing shaft and movably supported in one of said first and second jaws for selective axial movement between start and end positions in response to rotation of said firing shaft; wherein said firing member comprises a tissue cutting surface and a wedge for driving surgical staples from said surgical staple cartridge into forming contact with said anvil, said start position is a pre-fired position in which no staples have been driven from the surgical staple cartridge and said end position is a fired position in which all staples have been driven from the surgical staple cartridge; and a closure member in threaded engagement with said rotary input shaft such that rotation of said rotary input shaft in a first direction causes said closure member to move said second jaw to said closed position, said surgical stapling instrument being characterized in that said closure member remains in threaded engagement with said rotary input shaft to retain said second jaw in said closed position while continued rotation of said rotary input shaft in said first direction drives said firing member from said start position to said end position. a rotary input shaft; means for selectively applying rotary input motions to said rotary input shaft; a surgical end effector, comprising: a first jaw that comprises a surgical staple cartridge; a second jaw comprising an anvil and selectively movable relative to said first jaw between an open and closed position; a firing shaft operably interfacing with said rotary input shaft such that said firing shaft rotates in response to rotation of said rotary input shaft; a firing member in threaded engagement with said firing shaft and movably supported in one of said first and second jaws for selective axial movement between start and end positions in response to rotation of said firing shaft; wherein said firing member comprises a tissue cutting surface and a wedge for driving surgical staples from said surgical staple cartridge into forming contact with said anvil, said start position is a pre-fired position in which no staples have been driven from the surgical staple cartridge and said end position is a fired position in which all staples have been driven from the surgical staple cartridge; and a closure member in threaded engagement with said rotary input shaft such that rotation of said rotary input shaft in a first direction causes said closure member to move said second jaw to said closed position, said surgical stapling instrument being characterized in that said closure member remains in threaded engagement with said rotary input shaft to retain said second jaw in said closed position while continued rotation of said rotary input shaft in said first direction drives said firing member from said start position to said end position. a first jaw that comprises a surgical staple cartridge; a second jaw comprising an anvil and selectively movable relative to said first jaw between an open and closed position; a firing shaft operably interfacing with said rotary input shaft such that said firing shaft rotates in response to rotation of said rotary input shaft; a firing member in threaded engagement with said firing shaft and movably supported in one of said first and second jaws for selective axial movement between start and end positions in response to rotation of said firing shaft; wherein said firing member comprises a tissue cutting surface and a wedge for driving surgical staples from said surgical staple cartridge into forming contact with said anvil, said start position is a pre-fired position in which no staples have been driven from the surgical staple cartridge and said end position is a fired position in which all staples have been driven from the surgical staple cartridge; and a closure member in threaded engagement with said rotary input shaft such that rotation of said rotary input shaft in a first direction causes said closure member to move said second jaw to said closed position, said surgical stapling instrument being characterized in that said closure member remains in threaded engagement with said rotary input shaft to retain said second jaw in said closed position while continued rotation of said rotary input shaft in said first direction drives said firing member from said start position to said end position.