To test internal consistency, seventy-eight dog-owners rated both their own personalities and the personalities of their dogs using the Big Five Inventory (BFI), a standard test in personality research. Peers of the owners who were familiar with both the owners and the dogs also submitted a BFI for each, and statistical tests for internal consistency were computed across all four types of assessment. Correlations were very high, showing a substantial internal consistency in the measurements for both humans and their canine counterparts. To test consensus, simple correlations were computed between the owners’ ratings and peer informants’ ratings. Correlations were statistically significant for both human and canine species, suggesting a high consensus. Concerning correspondence, correlations were computed between owners’ personality ratings and the actual canine behaviors that were recorded in a field-test situation. Correlations were small but significant, again suggesting high correspondence. Tests were also conducted to successfully rule out any bias in ratings due to stereotypes about the personalities of certain breeds or ages of dogs.