A surgical instrument system, comprising: a handle comprising a handle frame; and a shaft assembly removably attached to said handle, said shaft assembly comprising: an end effector; a release actuator comprising a lock, wherein said release actuator is movable between a first position and a second position, wherein said lock is engaged with said handle when said release actuator is in said first position, and wherein said lock is disengaged from said handle when said release actuator is in said second position; and characterized in that: said handle frame comprises a recess; and said shaft assembly further comprises: a catch configured to engage said recess of said handle when said release actuator is moved from said first position to said second position when said shaft assembly is being detached from said handle, wherein said catch is disengaged from said recess of said handle upon an additional manipulation of said release actuator from said second position to said first position. a handle comprising a handle frame; and a shaft assembly removably attached to said handle, said shaft assembly comprising: an end effector; a release actuator comprising a lock, wherein said release actuator is movable between a first position and a second position, wherein said lock is engaged with said handle when said release actuator is in said first position, and wherein said lock is disengaged from said handle when said release actuator is in said second position; and characterized in that: said handle frame comprises a recess; and said shaft assembly further comprises: a catch configured to engage said recess of said handle when said release actuator is moved from said first position to said second position when said shaft assembly is being detached from said handle, wherein said catch is disengaged from said recess of said handle upon an additional manipulation of said release actuator from said second position to said first position. an end effector; a release actuator comprising a lock, wherein said release actuator is movable between a first position and a second position, wherein said lock is engaged with said handle when said release actuator is in said first position, and wherein said lock is disengaged from said handle when said release actuator is in said second position; and characterized in that: said handle frame comprises a recess; and said shaft assembly further comprises: a catch configured to engage said recess of said handle when said release actuator is moved from said first position to said second position when said shaft assembly is being detached from said handle, wherein said catch is disengaged from said recess of said handle upon an additional manipulation of said release actuator from said second position to said first position. said handle frame comprises a recess; and said shaft assembly further comprises: a catch configured to engage said recess of said handle when said release actuator is moved from said first position to said second position when said shaft assembly is being detached from said handle, wherein said catch is disengaged from said recess of said handle upon an additional manipulation of said release actuator from said second position to said first position. a catch configured to engage said recess of said handle when said release actuator is moved from said first position to said second position when said shaft assembly is being detached from said handle, wherein said catch is disengaged from said recess of said handle upon an additional manipulation of said release actuator from said second position to said first position.