Abstract: A wheelchair apparatus is provided for selectively positioning the operator from a sitting position to a standing position or a reclining position. The wheelchair apparatus includes a frame for supporting the operator's body in a reclined, sitting, and standing position. A single positioning actuator is used to selectively move the operator in the frame. A programmable controller controls the operation of both the chassis drive motors and the positioning actuator. The frame and chassis components are interconnected to achieve the desired positioning with a minimum number of electro-mechanical components. A sliding back frame is provided to eliminate shear forces on the back of the operator. The foot rest and frame are shifted towards the rear of the wheelchair when the operator is moved to a standing position such that the weight of the operator is over the axis of the large front wheels.