Abstract: A wheelchair or walker apparatus is disclosed and includes a frame having a base portion and spaced side portions to define a space for receiving an operator's body. A device is provided for supporting the frame above a ground surface for movement therealong and includes a mechanism for moving the apparatus over the ground surface. The movement mechanism includes a device for maintaining contact with a ground surface when moving over uneven terrain. The movement mechanism can be maintained in a preferred alignment. A device is provided to permit an operator within the space to control movement of the apparatus along the ground surface. A seat assembly supports and selectively moves an operator between a seated position and a substantially upright position within the apparatus and permits the operator to control and move the apparatus over the ground surface from both the fully seated position as well as the substantially upright position.