A ballast control integrated circuit for driving at least one gas discharge lamp comprising a first oscillator circuit for producing a first oscillating signal; a driver circuit for driving first and second output transistors connected in a half bridge configuration; the driver circuit being provided with pulsed signals derived from the first oscillating signal for generating pulsed drive signals for driving the first and second transistors; and a dimming control circuit responsive to a dimming input signal to drive the driver circuit such that the driver circuit provides the pulsed drive signals in bursts thereby to dim the lamp in dependence on the level of the dimming input signal. The ballast control integrated circuit also provides overcurrent and overvoltage sensing and allows master/slave operation.