In three experiments, two-event sequences were presented as discriminative stimuli for the key pecking of pigeons during a later test period. The purpose of these experiments was to evaluate the stimulus control exerted by saliency, primacy, recency, and, especially, temporal order in discriminations among two-event sequences. In Experiments 1 and 2, reinforcement for responding to the test stimulus depended on the prior occurrence of only one of several sequences of colored lights. In Experiment 3, reinforcement depended both on the sequence of colors and on the particular test stimulus that followed. Two phases in the pigeon's differentiation of two-event sequences were tentatively identified. Control by recency was stronger than by primacy during the first phase. Control by order increased and control by recency decreased during the second phase. The results left little doubt that pigeons can represent and remember the order of a recent series of events.