The concept of evidence is linked to health campaigns in several ways. First, ethical and cost-effectiveness considerations suggest that campaign-related decisions should be based on the best scientific evidence available, instead of on practitioners' gut feelings. For example, decisions about message construction strategies and about appropriate message dissemination channels should be grounded in systematic research evidence, preferably meta-analytic reviews. Second, health campaigns should only advocate evidence-based health behavior recommendations for relevant health threats. Third, central campaign claims should be substantiated with conclusive evidence in order to foster persuasion.