A surgical stapling instrument including a staple sled which can be advanced and/or retracted relative to first and second jaw members, wherein the staple sled can be configured to deploy staples from a staple cartridge in one of the first and second jaw members. In at least one embodiment, the other of the first and second jaw members can include an anvil having at least one forming surface which can be configured to deform the staples as they are deployed from the staple cartridge. In at least one form of the invention, the anvil can be movably adjustable relative to the staple cartridge in order to adjust the distance in which the staples are deformed. In various embodiments, the anvil can be adjusted by a slidable adjusting plate and/or a rotatable cam.