Abstract: A portable reversible chair apparatus with pivotal connections enabling the device to be converted from a "posture" chair configuration to a conventional chair configuration simply and quickly. While the device is in the "posture" chair configuration adjustments are possible that allow users of different size to select the seat angle and the seat to knee rest distance which is most comfortable for them. The knee rest is designed to flex in the verticle plane allowing the seated user to shift weight and position comfortably and safely. The critical joints of the chair pivot thus eliminating racking of joints. Rigidity is derived from triangulation rather than from the size of the joints. The device is very stable due to its large base and sits well on an uneven surface because it rests on three points rather than the traditional four.