Loyalty has been researched in many areas, but little attention has been paid to whether loyalty is a unitary construct or differs across domains. We suggest that loyalty will differ across domains in accordance with the challenges our ancestors faced during their evolutionary history. We test this hypothesis by developing seven psychometric loyalty scales—each putatively assessing a different domain—and investigating whether there is significant individual variation across them. The proposed domains are loyalty to group, friend, romantic partner, kin, nation, sports team and brand. We found good internal consistency for all seven scales, and factor analysis indicated that the scales were distinct, supporting the hypothesis of distinct loyalty domains. We also found preliminary evidence for gender differences in two of the domains. This research illustrates the utility of an evolutionary perspective and should help future studies identify the contextual and dispositional factors contributing to loyalty.