An organic light-emitting device including a first electrode, a second electrode facing the first electrode, and an organic layer between the first electrode and the second electrode and including an emission layer, wherein the organic layer includes a first compound and a second compound; the first compound is represented by one selected from Formulae 1-1 to 1-4, and does not include a nitrogen-containing heterocyclic group that includes *═N—*′ as a ring-forming moiety, and the second compound is represented by Formula 2: