Abstract: A height-adjustable support assembly having the ability to vary the height of the support surface generally includes a base portion, a support surface, a first member interconnected with and extending upwardly from the base portion, and a second member interconnected with the support surface and movably engaged with the first member. The second member is movable from a first position, to position the support surface at a first height from the base portion, and an extended position, to position the support surface at a second height from the bottom surface. A support structure interconnected with the bottom surface, is provided for supporting the second member at an upper portion thereof when the second member is in the extended position, the upper portion being above an upper end of the first member.