A height-adjustable furnishing system includes a base component, a plurality of legs, a height adjustment mechanism, and a platform component. The base has a planar bottom surface and a top surface with a plurality of attachment points for pivotally attaching two, three or four legs. The height-adjustment mechanism is adjustably attached between the base component and at least one of the plurality of legs, or between a forward leg and a rear leg. A platform component is pivotally attached to the plurality of legs to form a parallelogram linkage when viewed from the side. The height-adjustment mechanism may include a gas spring, a cam clamp, a travel block, a release lever, a cable release, a release trigger and may also be hand- or foot-operated. The entire system folds to a generally planar configuration for storage. The legs are erect when they are approximately 10 degrees from vertical.