A method for determining the operativeness of a driver-assistance system of a vehicle, in particular a motor vehicle. The driver-assistance system has at least one light sensor and at least one camera sensor, which are developed and/or aligned on the vehicle in order to detect at least essentially the same environment. It is provided that at least one first brightness value ascertained by the light sensor is compared to at least one second brightness value ascertained by the camera sensor, and that the operativeness of the driver-assistance system is determined by the comparison of the brightness values.