Previous research and reviews on comparative advertising report mixed results. The authors report the results from a meta-analysis that examines the efficacy of comparative advertising. The analysis shows that comparative ads are more effective than noncomparative ads in generating attention, message and brand awareness, levels of message processing, favorable sponsored brand attitudes, and increased purchase intentions and purchase behaviors. However, comparative ads evoke lower source believability and a less favorable attitude toward the ad. Additional analyses of moderator variables find that market position (sponsor, comparison, and relative), enhanced credibility, message content, and type of dependent measure (relative versus nonrelative) affect some of the relationships between advertising format and cognition, brand attitudes, and purchase intentions. New brands comparing themselves to established brands appear to benefit most from comparative advertising.