Apparatus for monitoring and controlling the operation of one or more high intensity discharge (HID) lamps. An electronic HID lamp power supply is electrically connected to a power source and to the HID lamps. For each lamp, one or more sensors produce one or more output signals respectively representative of one or more parameters (such as light intensity, color temperature, power consumption, temperature, arc voltage, etc.) which respectively define one or more operational characteristics of the lamps. A programmable controller receives the sensors' output signals and programmatically responds by, for example, outputting to the power supply control signals for controlling operation of the lamps to cause a selected variation in a selected one or more of the sensed parameters, and/or by periodically logging information characteristic of an operational state of one or more of the lamps or the power supply at a selected time or times, and/or by producing diagnostic information characteristic of an operational state of one or more of said lamps or said power supply.