Many health- and risk-related behaviors have moral implications. Most obvious are altruistic behaviors like blood donation. However, issues related to promoting the wellbeing of friends and family members, such as being sure that they don’t drive drunk, and the generalized obligations that attend environmentally relevant behaviors like participating in recycling programs, also tap into moral concerns. For promoting such issues, moral appeals may be appropriate. Moral appeals are messages that acknowledge individuals’ evaluative beliefs about universal rights and wrongs. Appeals to morality produce a sense of obligation and responsibility because morals are viewed as self-evident facts. Three explanations for why people engage in moral behavior are discernible in current scholarship, each with implications for structuring moral appeals: activation of social expectations, activation of personal norms, and arousal of emotion. The first of these is based on the subjective expected utility tradition. From this perspective, the key to successfully encouraging morally relevant behavior is maximizing benefits and minimizing costs. Because prosocial behaviors are enforced by social sanctions, many of these costs and benefits are socially bestowed. Thus, altruism at its core is hedonism. Theories that focus on activation of personal norms, in contrast, contend that people sometimes make decisions to donate blood, demonstrate for healthcare reform, recycle, and so on simply because they view it as their duty and responsibility to do so. When people realize in a concrete situation that their actions have consequences for the welfare of others, and that they are personally responsible for those outcomes, personal norms for the specific case are generated from internalized moral values. In this view, a central concern with moral appeals is ensuring that messages are aligned with internalized norms and that relevance and personal responsibilities are clearly communicated. Finally, theories of emotional arousal stress that although cognitive appraisals of personal and social norms are necessary, they are insufficient to incite people to selfless behavior. Rather, people engage in helping or altruistic behavior because moral appeals are emotionally arousing. Emotions associated with such appeals include empathic concern and guilt. Guilt appeals especially have been found to be as effective in eliciting compliance when behaviors have moral significance as other popular compliance-gaining strategies. Positive emphasis on responsibility and induction of hypocrisy are also techniques that rely on the appeal to moral beliefs.