A staple cartridge assembly , comprising: a cartridge body , comprising: a deck comprising a proximal end and a distal end; a longitudinal slot defined in said deck , wherein said longitudinal slot is configured to receive a firing member; a first longitudinal row of staple cavities ; and a second longitudinal row of staple cavities (434a; 434b), wherein said first and second longitudinal rows of staples cavities are laterally offset; a sled movable toward said distal end by the firing member during a firing stroke; a plurality of first staples , wherein one of said first staples is removably stored in each staple cavity of said first longitudinal row, wherein each said first staple is comprised of a bent wire; a plurality of staple drivers configured to support said first staples , wherein said sled is configured to engage said staple drivers to eject said first staples from said first longitudinal row of staple cavities during the firing stroke; and a plurality of second staples formed from flat stock; characterized in that one of said second staples is removably stored in each staple cavity (434a; 434b) of said second longitudinal row, wherein each said second staple comprises an integrally-formed driver , and wherein said sled is configured to directly engage said integrally-formed drivers of said second staples and eject said second staples from said second longitudinal row of staple cavities (434a; 434b) during the firing stroke. a cartridge body , comprising: a deck comprising a proximal end and a distal end; a longitudinal slot defined in said deck , wherein said longitudinal slot is configured to receive a firing member; a first longitudinal row of staple cavities ; and a second longitudinal row of staple cavities (434a; 434b), wherein said first and second longitudinal rows of staples cavities are laterally offset; a deck comprising a proximal end and a distal end; a longitudinal slot defined in said deck , wherein said longitudinal slot is configured to receive a firing member; a first longitudinal row of staple cavities ; and a second longitudinal row of staple cavities (434a; 434b), wherein said first and second longitudinal rows of staples cavities are laterally offset; a sled movable toward said distal end by the firing member during a firing stroke; a plurality of first staples , wherein one of said first staples is removably stored in each staple cavity of said first longitudinal row, wherein each said first staple is comprised of a bent wire; a plurality of staple drivers configured to support said first staples , wherein said sled is configured to engage said staple drivers to eject said first staples from said first longitudinal row of staple cavities during the firing stroke; and a plurality of second staples formed from flat stock; characterized in that one of said second staples is removably stored in each staple cavity (434a; 434b) of said second longitudinal row, wherein each said second staple comprises an integrally-formed driver , and wherein said sled is configured to directly engage said integrally-formed drivers of said second staples and eject said second staples from said second longitudinal row of staple cavities (434a; 434b) during the firing stroke. <EOS>