A chair back assembly includes a back shell member comprising a laterally extending top and bottom portions and a pair of longitudinally extending side portions extending between the top and bottom portions and cooperating therewith to define an open space therebetween, a cover having a first surface adapted to support a seated user and a second surface opposite the first surface, wherein the cover is positioned over the back shell member to cover at least a portion of the open space; and a back frame assembly operably supporting the back shell member and moveable between an upright position, and a reclined position, wherein the back frame assembly causes the back shell to flex in a fore-to-aft direction as the back frame assembly is moved between the upright and reclined positions independent of an external force being exerted on the back shell member.