While humor has been extensively studied in commercial marketing, there is less known about how humor functions in the context of a public health campaign. This dissertation addresses that gap by exploring the use of humor in public health messaging through (1) a systematic review and meta-analysis of the literature, (2) a content analysis of public-health related print ads from the Ad Council, and (3) an experiment testing the role of humor styles in the effectiveness of humorous anti-binge drinking messages. The systematic review and meta-analysis assembled all the currently known research on humor in public health messaging. Overall, the success of humor depended on many factors, including the health topic and characteristics of the audience, and humor was found to not differ drastically from other appeal types in its influence on key persuasion outcomes. The meta-analytic component of this review found that humor had a positive impact on ad liking and behavior and a negative impact on perceived self-efficacy and intention, with only self-efficacy demonstrating a statistically significant difference between the appeal types. In the content analysis, Ad Council ads spanning 70 years of public health messaging were evaluated in order to understand the utilization of important communication elements in health communication campaigns. A sample of print ads was assembled, and ads were coded for theoretical constructs, ecological level, emotional appeal, and the presence of humor. The sample included a variety of campaign topics, ranging from drunk driving to polio vaccination to child abuse. Overall, campaigns were found to most often lack response efficacy information, and the presence of specific behavioral suggestions regarding the health issue decreased over time in favor of contact information. Most campaigns targeted the individual level, with few targeting organizational, policy or other systems-level changes necessary to facilitate most (if not all) public health behaviors. The experiment examined the role of matching ad humor styles to individual humor styles in humorous anti-binge drinking ads aimed at college students. Those with detrimental humor styles were found to perceive messages matched to their humor style as more humorous than messages not matched to their humor style. Perceived humor was found to be negatively associated with message rejection and positively associated with likelihood of sharing the message. This study re-affirms the importance of ensuring humor campaigns are actually perceived as humorous by the audience. Overall, this dissertation suggests that humor should be used in well-tested public health campaigns in order to realize its potential benefits for affecting health behaviors.