An occupant detection system for detecting an occupant within a vehicle includes a sensor for sensing movement or acceleration of the vehicle, first and second processors and a decider. The sensor generates a sensor output. The first processor processes the sensor output in a first manner and generates a first output indicative of the possibility of the presence of an occupant within the vehicle. The second processor processes the sensor output in a second manner and generates a second output indicative of the possibility of the presence of an occupant within the vehicle. The decider processes the first and second outputs and determines whether the combination of the first and second outputs is indicative of an occupant in the vehicle.