An organic light emitting display includes a display panel including sharing pixel groups each including at least one unit pixel, a gate driving circuit generating sensing signals for initializing the unit pixels, and a data driving circuit which generates an initialization voltage to be applied to the unit pixels and outputs the initialization voltage through a plurality of initialization voltage supply channels. When the sensing signals each having a pulse width of N horizontal periods (where N is a positive integer equal to or greater than 2) are shifted while overlapping each other by (N−1) horizontal period, N initialization voltage supply channels are assigned to a plurality of vertically adjacent sharing pixel groups. N sharing pixel groups, being driven to overlap each other in response to the sensing signals, among the vertically adjacent sharing pixel groups are connected to different initialization voltage supply channels.