A pneumatic support system for a wheelchair is provided herein. An implementation includes a support unit that supports a portion of the body of a user, a control unit that permits the user to control whether the support unit gets inflated or deflated, and a compressor that provides pressurized air to the support unit to inflate the support unit. The wheelchair has a valve, such when the user indicates that the support unit is to be inflated, the control unit sends a signal to the valve to move the valve to a first position, thereby permitted the pressurized air to reach the support unit. The support unit may be implemented in a variety of ways, and may be one of many support units. In one implementation, the support unit supports a thoracic portion of the user's body. In another implementation, the wheelchair has one or more thoracic support units, which may be disposed on opposite sides of the thoracic portion of the user's body, and one or more pelvic support units, which may be disposed on opposite sides of the user's pelvis. The thoracic support units and or the pelvic support units may be pivotally attached to the back support of the wheelchair.