The presence of a child restraint seat on a vehicle seat is detected by movement of a pair of anchors from a first position to a second position when the child restraint seat is coupled with straps to the anchors. The anchors are pivotally or deflectively mounted on a cross bar which extends between side frame members within the back of the vehicle seat. Upon a sensor detecting the presence of the child restraint seat, an associated air bag is disabled so that the air bag will not be deployed against a child sitting in the child restraint seat if the car is in an accident. Upon removing the child restraint seat, the anchors return to the first position in which the sensor again enables the air bag for deployment because, in the absence of a child restraint seat, an occupant of the seat is more likely to be an adult than a child.