Wild populations of a small neotropical primate, Geoffroy's tamarin (Saguinus geoffroyi), were studied through 30-s instantaneous observational sampling to identify different canopy habitats used by this tamarin. Tree and shrub canopies were sampled in randomly selected plots and in nearby plots that tamarins were observed to use in the forests of Agua Clara, Panama (28 d, 59 100-m2 plots, 32.25 h of tamarin observations, 27 tamarins in total), and in the nearby forests of Barro Colorado Island (49 d, 29 100-m2 plots, 29.6 h of tamarin observations, 14 tamarins in total). Light penetration through the canopy, ambient temperature and humidity, presence of other primates, stem diameters, plant life-forms, distribution of woody flora, abundance of fleshy fruits and arthropods typically consumed by tamarins and abundance of thorny vegetation and biting arthropods in plots used by tamarins were compared with control plots. Habitats used by tamarins had significantly shorter distances between adjacent tree canopies and between canopies and the ground. There was a random distribution of large insects and fleshy fruits that tamarins are known to eat. Habitat selection by tamarins may not be influenced by spiny vegetation, but tamarins may avoid areas with abundant hooked thorns and blood-sucking arthropods. Mobility along runways in various tiers of a rain-forest canopy may be of primary importance, with local abundance of food being a secondary consideration in habitat selection by this small primate.