Abstract: An articulated tonneau cover having a center panel and right and left corner panels that are pivotally connected to the center panel. Right and left corner panels are moved between an extended position in which the corner panels are adjacent to right and left edges of the center panel and a retracted position in which the right and left corner panels are inboard of the center panel. A motor drives the corner panels between their extended and retracted positions. Cam ramp pivots shift the corner panels vertically as they are pivoted relative to the center panel so that the corner panels are substantially coplanar with the center panel when they are in their extended position. When the corner panels are in their retracted position they are disposed below and parallel to the center panel. Side counter panels are provided forward of the corner panels and are moved in conjunction with the center panels by means of a cylinder and four bar link.