Abstract: An invalid chair such as a wheelchair for partially disabled paraplegic persons has a pivotally mounted seat mechanically coupled to a movably mounted foot rest structure. By shifting and altering his weight distribution, the chair occupant can depress the foot rest structure from a raised foot-supporting position to a lowered ground-engaging position. At the same time, the seat moves angularly upward and forwardly from a substantially horizontal orientation in a seating support position to a substantially upright back-supporting orientation in a relatively displaced standing support position. Thus, the seat exerts a supporting pressure from behind to the body of the chair occupant and assists his movement in rising from a sitting posture to a standing posture. The arrangement also permits the chair occupant likewise to control reverse movement in changing from a standing posture to a sitting posture by controlling his weight distribution and pressure applied to the foot rest structure.