An display and a driving method thereof are capable of displaying images of desired luminance. The display includes a scan driver connected to scan lines, a data driver connected to data lines, pixels connected to the scan lines and the data lines, the pixels being adapted to generate light while supplying an electric current from a first power source to a second power source, a power source unit for generating the first power source, and a compensating unit adapted to control a voltage value of the first power source.