Purpose - Although there is considerable scholarly research on advertising self-regulation in the USA, there is no research at all on the unique problems that comparative advertising created for those involved in the industry's self-regulation. This study aims to address this gap in the literature with an historical analysis of the industry's efforts to respond to the widespread adoption of comparative advertising during the twentieth century. Design/methodology/approach - The study's primary and secondary sources consist of nearly 640 articles collected from historical and contemporary trade journals. The analysis focuses on two research questions: When did calls for the reform and regulation of comparative advertising appear, why did they appear, and who did advertisers believe should be responsible? and Why did advertisers and industry observers believe comparative advertising should be regulated, and what were the consequences of their self-regulation efforts and initiatives? Findings - The paper finds that industry calls for comparative advertising reform began to appear during the Depression and peaked during the most contentious period of self-regulation, the 1970s. The findings show that during the 1930s, members of the industry mostly abandoned their efforts to manage what they considered unfair business practices, including explicit comparative advertising, by shaping government policy. The findings also reveal that the issues of disparagement of competitors and the misappropriation of their brand names and trademarks set the stage for an extraordinary conflict between the industry, its self-regulators, and the Federal Trade Commission. Originality/value - The findings offer some new and interesting insights into the consequences that can occur when advertisers choose to employ explicit comparative advertising, or what has been called "the hardest sell of all"; the history of advertising self-regulation in the USA; and the complex relationships among consumerism, political and economic ideology, and industry self-regulation.