An organic light emitting display includes a pixel circuit that compensates for variations of the threshold voltage of a driving transistor. The organic light emitting display includes a scan driver, a data driver, a power source unit, and a plurality of pixels. If a pixel is assumed to be positioned in an ith (i is a natural number) horizontal line, that pixel includes an organic light emitting diode (OLED), a first transistor coupled between a power source line and the OLED, a second transistor having a gate electrode coupled to an ith scan line for supplying the data signal to the first transistor, a third transistor coupled between the OLED and the first transistor and having a gate electrode coupled to an ith emission control line, and a storage capacitor coupled between the gate electrode of the first transistor and an anode electrode of the OLED.