Evidence of observational learning (social learning) is present in many species. One such task is the one-trial taste-avoidance task, in which Actor chicks peck a bead coated with an aversant substance. Observer chicks learn to avoid beads that are similar in appearance to the one presented to the Actors. It has been firmly established that active learning of the one-trial taste-avoidance task is dependent on a constrained level of glutamate receptor activation. The current study examined the effects of memantine, a noncompetitive N-methyl-D-aspartate receptor antagonist, on the learning by Observers. Memantine produced an inverted U-shaped dose-dependent response curve; 1.0 mmol/l memantine produced significant improvement. These results demonstrate that memantine influences memory formation for observational learning in the day-old chick and support the hypothesis that memantine can improve memories by altering levels of glutamate during memory formation.