Abstract A sample of 65 Tucano adolescents living in the Amazon region of Colombia were administered a 26-item handedness questionnaire. All subjects were right-handed. A factor analysis of the data indicated a factor structure rather different from that seen in North Americans, although both skilled and unskilled handedness factors were seen. Other factors related to specific tool use and to strength. These data indicate that positive reinforcement for right-hand use can modify patterns of handedness, and may well alter the relations among different items. The data suggest that hand preference can be modified through positive reinforcement at an appropriate age, and that hand preference is the precursor of skill differences rather than vice versa.