A posture monitoring device 10 for use with a seat 100 comprises at least two pressure sensors 18, 20, a mount 12 for movably securing the pressure sensors 18, 20 to a seat back 102, the mount 12 including a hook for fitting over the seat back 102, and output means 22 for alerting when the pressure measured on at least one of the pressure sensors 18, 20 falls outside of a predetermined range.
