An organic light-emitting device including: a first electrode; a second electrode; and an organic layer including an emission layer between the first electrode and the second electrode. The organic layer may include at least one compound selected from a first compound and a second compound, in addition to a third compound. The first compound is represented by one selected from Formulae 1-1 and 1-2, the second compound is represented by Formula 2, and the third compound is represented by one selected from Formulae 3-1A and 3-2A: