Publisher SummaryCentral to the theoretical model of personal normative influences on altruism presented in this chapter is the idea that altruistic behavior is causally influenced by feelings of moral obligation to act on one's personally held norms. Research supporting this central tenet of the model has demonstrated associations between personal norms and behavior rather than causal relations. These associations are partly causal because the associations appear primarily in the presence of personality conditions conducive to norm activation and are absent when personality conditions are conducive to deactivation, and attributes of personal norms (e.g., centrality, stability, and intensity) relate to altruism singly or in combination, in ways predicted when the causal impact of anticipated moral costs on behavior is assumed. Studies show that variations in situational conditions conducive to activation of moral obligation also influence the relationship between personal norms and behavior. There is ample evidence that variables that foster movement through the activation process—according to the theoretical model—are themselves related to altruistic behavior (e.g., seriousness of need and uniqueness of responsibility). The study of how personal norms are related to altruism is a part of a larger enterprise—the investigation of attitude–behavior relations in general.