A supplemental tailgate extends from the tailgate frame of a pickup truck and is positionable in multiple orientations to provide a variety of uses, including as an extension of the pickup truck bed. The supplemental tailgate includes a cross member connected between two telescoping supports, which forms a part of the tailgate molding when stored within the main tailgate structure. A lock rod assembly interconnects the supplemental tailgate and the body of the pickup truck to stabilize the position of the extended supplemental tailgate when positioned perpendicular to the opened main tailgate. The lock rod assembly can be formed as flexible cables that can be housed within the cross member for easy deployment when needed. The lock rod assembly can also be formed as fixed length rods that are pivotally mounted on the cross member and stored within the cross member for easy deployment.