• Cerebral dominance is reflected in man by a seemingly inborn preference for the right hand in 80% to 90% of mature individuals. However, not all of the factors that govern human cerebral dominance are clearly understood. We studied rhesus monkeys to determine if hand preference in that primate also reflected a form of cerebral dominance and hence could be used to elucidate cerebral hemispheric asymmetry as it appears in man. Shortterm experiments provided positive evidence that experiential and environmental factors were sufficient to explain the originally observed hand preference in individual and groups of monkeys. We then demonstrated that training readily induced new hand preferences, further suggesting that monkey hand preference is primarily shaped by experience. Our evidence failed to support previous conclusions of right or left preference as a characteristic of the species. Although handedness based on inborn morphological and functional hemispheric asymmetry as seen in man was not demonstrated, the preferences induced by training in our monkeys were systematically altered by contralateral association cortical removals, suggesting that asymmetries of cerebral function may be acquired in monkeys.