An organic light emitting diode display compensates for a threshold voltage of a thin-film driving transistor to improve display quality. The display includes a light emitting cell connected between a high-level voltage source and a first node. A driving transistor is connected between the first node and a ground voltage source to control a current, which flows in the light emitting cell, by using a voltage applied to a gate terminal of the driving transistor. A data driving circuit applies a data voltage of first polarity to the gate terminal of the driving transistor to shift a threshold voltage of the driving transistor from a reference value to the voltage of first polarity. A compensation circuit supplies a compensation voltage of second polarity to the gate terminal of the driving transistor to shift the threshold voltage of the driving transistor from the voltage of first polarity to the voltage of second polarity, and then supplies a constant current to the gate terminal of the driving transistor to restore the threshold voltage of the driving transistor to the reference value.