An automatic headlamp control system includes an image sensor, such as an imaging array sensor, and a control. The image sensor is operable to capture an image of a scene forwardly of the vehicle and the control is operable to process the image to determine if any light sources in the captured image are indicative of headlamps of oncoming vehicles or taillights of leading vehicles. The control may adjust the state of the headlamps between a high beam state and a lower beam state in response to such processing of the captured image. The control may be operable to distinguish a reflection of the controlled vehicle's headlamps from the taillights of a leading vehicle, headlamps of an oncoming vehicle, other light sources, and/or reflections from other light sources via recognition of a signature, code or pattern superimposed on the light output of the headlamps of the controlled vehicle.