A posture correcting chair having a back rest assembly providing mounting attachments for a head or neck rest, a lumbar support, at least one arm rest, and a posture retainer and supported by a seat assembly. The headrest, lumbar, seat and back support all adjust to allow a user to distribute their weight about a greater number of surfaces for adaptive comfort. A posture retainer affixed to the back rest assembly dynamically adjusts to the contour of a user's body based on force and pressure created while seated to provide active posture correction for a user to prevent slumping or slouching. A knee rest assembly is attached to rail system on a lower end of chair the base platform to provide additional support surfaces. The seat and knee rest assembly include heating, cooling or vibrating or massaging.