AbstractEvidence indicates that primate species differ not only in social structure and concordant social propensities, but also in their approach toward novel objects, environments, and procedures. These differences in response dispositions have been described as being based on differences in characteristic stances toward the environment, also called temperaments. This report extends previous comparative primate research by describing behavioral contrasts observed among males of two macaque species, liontailed and cynomolgus macaques. The lion‐tails demonstrated more interest in other animals, more vigilance and instrumental behavior, and more readily adapted to training to enter a small and unfamilar cage than the cynomolgus. These results suggest temperamental differences between the two species. Lion‐tails may be characterized as bold, curious, and instrumental in their approach to the environment, while cynomolgus may be characterized as more passive or “reserved”. These differences may form the basis for the well‐developed sensorimotor abilities observed in liontails such as the manufacture and use of tools, and may also be related to their highly omnivorous diet. © 1993 Wiley