Complex phenomena such as advertising are difficult to understand. As a result, extensive and repeated testing of diverse alternative reasonable hypotheses is necessary in order to increase knowledge about advertising. Laboratory and field experiments, as well as quasi-experimental studies, are needed. Fortunately, much useful empirical research of this kind has already been conducted on how to create persuasive advertisements. A literature review, conducted over 16 years, summarized knowledge from 687 sources that covered more than 3,000 studies (Armstrong 2010 https://link.springer.com/book/10.1057/9780230285804 https://a.co/d/hqxj4Ij). The review led to 195 principles (condition-action statements) for advertising. We were unable to find any of them in a convenience sample of nine advertising textbooks. The textbooks tended to ignore evidence on persuasion. Of the more than 6,500 sources referenced in these textbooks, only 24 overlapped with the 687 used to develop the principles. By using the evidence-based principles, practitioners may be able to increase the persuasiveness of advertisements. Relevant evidence-based papers have been published at the rate of 20 per year from 2000 to 2010. The rate of knowledge accumulation could be increased if journal editors invited papers with evidence-based research findings.