A sensor for sensing when a latch of a child safety seat is coupled to a seat assembly of a vehicle. The sensor may include a first housing member that is mounted to a seat frame of the vehicle. The sensor may also include a second housing member that can move relative to the first housing member. A sensor subassembly may sense the relative movement of the second housing member. The latch of the child safety seat can be snapped onto a ring of the second housing member and subsequently tightened to secure the child seat to the vehicle. Coupling the child seat to the ring moves the second housing member relative to the first housing member. This movement is sensed by the sensor which provides an output signal. The output signal can be processed to provide an indication to the vehicle driver that the child seat has been coupled to the seat, and/or disable an airbag and/or disable a seat movement device.