Golden lion tamarins (Leontopithecus rosalia) and Wied's marmosets (Callithrix kuhli) exhibited adaptive differences in performance on several distinct memory tasks. On both an open-field analogue of a radial arm maze and a spatial delayed matching-to-sample task, the marmosets performed better than the tamarins after short (5-min) retention intervals, but only the tamarins continued to perform above chance after long (24-or 48-h) retention intervals. The marmosets also reqUired less training than the tamarins did to learn a color memory task, but again only the tamarins performed above chance when the retention interval was increased to 24 h. The results of these experiments are consistent with predictions based on knowledge of the feeding ecology of these species in the wild and raise the possibility that they possess different visuospatial memory abilities specialized for tracking the spatial and temporal distribution of their principal foods.