A four-bar linkage for an articulation assembly adapted for use with a surgical instrument is disclosed. The first link is in the form of an actuation lever which pivots transversely to the longitudinal axis of the instrument. The second and third links are operatively connected to the first link. The fourth link is in the form of an end effector for the instrument, and it is rotatably attached to the second and third links for movement transverse to the longitudinal axis. When the first link is pivotally rotated, a driver assembly causes the second and third links to move in tandem generally parallel to the longitudinal axis of the instrument in opposite directions. Consequently, the end effector rotates in the same direction as that of the actuation lever from an unarticulated position to an articulated position. The four-bar linkage is simple and efficient, and eliminates the need for a conventional central pivot for the articulation joint. By making the linkage the primary structural support of the end effector, clearance can be provided centrally between the second and third links to allow for the passage of additional linkages and members which are needed to actuate the end effector to carry out various surgical functions.