Disclosed is an apparatus that serves to alert an individual to a change in the individual's posture. A responder that provides an alerting signal to the wearer of the apparatus is mounted on an elastic band that is worn by the individual. When the individual's posture is correct, there is no alerting signal. When the individual's posture changes, and in particular by slouching, the elastic band stretches, a switch is then closed in the responder thereby completing an electrical circuit which generates an alerting signal such as a small buzz or tone to the wearer. In response to this signal, the wearer can correct posture and thus turn off the alerting signal.