Abstract: Systems and methods for determining conditions of a seat within a vehicle and modifying the operation of at least one safety system or device in response to the conditions of the seat. The system includes a sensor module located in a seat-back of the seat, a control module, and at least one safety system. The sensor module includes one or more accelerations sensors for measuring the acceleration of the seat along first, second, and third axes with respect to the vehicle (e.g., longitudinal, transverse, and vertical directions with respect to the vehicle). The signals generated by the acceleration sensor are sent to the control module, which uses the signals to determine a plurality of conditions of the first seat. The conditions of the seat include, for example, a seat-back tilt angle, a seat-shock (e.g., from a collision), vehicle dynamics (e.g., vehicle acceleration and velocity in multiple directions), and a vehicle rollover condition.