A surgical stapling instrument assembly, comprising: a shaft; a plurality of staple cartridges positioned within said shaft, wherein each said staple cartridge comprises a cartridge body and a plurality of staples; a firing member configured to move along a firing path between proximal and distal positions; a first jaw comprising: a proximal portion attached to said shaft; a distal portion; a channel configured to receive a said staple cartridge; and a plurality of staple drivers, wherein said firing member is configured to engage said staple drivers and move each said staple driver from a first position into a second position as the firing member is moved from said proximal portion to said distal portion, and wherein said firing member is configured to engage said staple drivers and move each said staple driver from said second position into said first position as the firing member is moved from said distal portion to said proximal portion; a second jaw comprising an anvil, wherein said staples are configured to contact said anvil when said staples are deployed; and a cartridge driver configured to sequentially advance a said staple cartridge into said channel; wherein said firing member comprises at least one inclined surface (171, 174) and at least one declined surface, wherein each said staple driver comprises: a lifting surface (181, 183) configured to be contacted by said at least one inclined surface (171, 174) when said firing member moves said staple drivers between said first position and said second position; and a lowering surface configured to be contacted by said at least one declined surface when said firing member moves said staple drivers between said second position and said first position. a shaft; a plurality of staple cartridges positioned within said shaft, wherein each said staple cartridge comprises a cartridge body and a plurality of staples; a firing member configured to move along a firing path between proximal and distal positions; a first jaw comprising: a proximal portion attached to said shaft; a distal portion; a channel configured to receive a said staple cartridge; and a plurality of staple drivers, wherein said firing member is configured to engage said staple drivers and move each said staple driver from a first position into a second position as the firing member is moved from said proximal portion to said distal portion, and wherein said firing member is configured to engage said staple drivers and move each said staple driver from said second position into said first position as the firing member is moved from said distal portion to said proximal portion; a proximal portion attached to said shaft; a distal portion; a channel configured to receive a said staple cartridge; and a plurality of staple drivers, wherein said firing member is configured to engage said staple drivers and move each said staple driver from a first position into a second position as the firing member is moved from said proximal portion to said distal portion, and wherein said firing member is configured to engage said staple drivers and move each said staple driver from said second position into said first position as the firing member is moved from said distal portion to said proximal portion; a second jaw comprising an anvil, wherein said staples are configured to contact said anvil when said staples are deployed; and a cartridge driver configured to sequentially advance a said staple cartridge into said channel; wherein said firing member comprises at least one inclined surface (171, 174) and at least one declined surface, wherein each said staple driver comprises: a lifting surface (181, 183) configured to be contacted by said at least one inclined surface (171, 174) when said firing member moves said staple drivers between said first position and said second position; and a lowering surface configured to be contacted by said at least one declined surface when said firing member moves said staple drivers between said second position and said first position. a lifting surface (181, 183) configured to be contacted by said at least one inclined surface (171, 174) when said firing member moves said staple drivers between said first position and said second position; and a lowering surface configured to be contacted by said at least one declined surface when said firing member moves said staple drivers between said second position and said first position.