An organic light emitting display, and a method of driving the same, controls the voltage of a second power source in accordance with an ambient temperature. The organic light emitting display includes a driver IC configured to drive a pixel unit and to generate a control signal in accordance with an ambient temperature, and a DC-DC converter configured to generate a first power source and a second power source from an input voltage, to change a voltage of the second power source in accordance with the control signal from the driver IC, and to output the changed voltage of the second power source and the first power source.