A dual purpose ambient light sensor. More particularly, an ambient light sensor may be provided on an electronic device to aid in controlling the brightness of the illuminators of the device. The ambient light sensor may be mounted in such a way as to detect ambient light when the electronic device is opened or closed so that the device may control the brightness of the illuminators of the device, whether the illuminators are mounted on the outer or inner shell of the device. Further, when the display is closed, the sensitivity of the ambient light sensor may be adjusted appropriately to account for the lesser amount of light that may reach the sensor. Finally, a spacer or light pipe may be provided to allow ambient light to reach the sensor to provide an accurate ambient light reading when the device is in the closed position.