Extant research on cobranding does not examine when and why complementarity or similarity between cobranding partners can be more effective. This research examines consumers' reactions to cobranded partnerships that feature brands with either complementary or similar attribute levels, both of which are common in the marketplace. The results of six experiments show that consumers' evaluations vary as a function of concept combination interpretation strategy (property mapping or relational linking) and whether cobranded partners have complementary or similar attributes. Specifically, when consumers use property mapping, they evaluate cobranded partnerships with complementary (vs. similar) attribute levels more favorably. In contrast, when using relational linking, they evaluate cobranded partnerships with complementary (vs. similar) attribute levels less favorably. The results also reveal that the breadth of the host brand (broad vs. narrow) and the type of advertising influence the extent to which consumers are likely to use property mapping or relational linking in evaluating cobranded partnerships.