Why are humans norm-addictive and what are the functions of norms in human cultures? This chapter inquires into social norms from the perspective of cultural anthropology. Cultural anthropologists investigate norms through long-term fieldwork of peoples in their natural settings and by systematic cross-cultural comparison. Core elements of the holistic anthropological concept of culture are concerned with social norms. The principal function of social norms is to allow for effective, coordinated, and predictable action in human collectives. Cross-cultural studies reveal that a strong orientation toward norms is universal. Most norms are learnt through socialization from family members or other kindred. Recent studies revealed that norms locally regarded as crucial often are transmitted by emotionally intensive teaching. The chapter also critically discusses some problems of interdisciplinary research into norms, such as the different understandings of “expected” and the dissimilar empirical accessibility of norms as psychic orientations among different primates.