An organic light emitting diode (OLED) display device and a method of driving the same are provided. A time point at which each of transistors is turned on is controlled without using an additional transistor so that a node connected to a source electrode of a driver transistor can be floated, and a node connected to a gate electrode of the driver transistor can be initialized to an initialization voltage level. Thus, initialization characteristics can be improved to enhance degradation of response characteristics and luminance, and a threshold voltage of the driver transistor and occurrence of a ripple at a high-potential voltage terminal can be compensated.