Cultural constructions of sex and sexuality are the primary building blocks of social organisation. Anthropological discussions of sexuality tend to revolve around the various aspects of social organisation, such as the lifecycle, gendered identities, and personhood. These discussions are informed by the cultural meanings we impute to differences in biological sex and reproduction, and the ways in which these meanings influence social organisation, personhood, and power. In this module, we will consider cultural constructions of sex and sexuality as these inform certain aspects of social organisation such as kinship and marriage. We will attempt to develop an anthropological perspective on the interplay between sex, culture and society. To this end, we will examine the physiology of sexuality, and then consider different theoretical perspectives on human sexuality as reflected in cross-cultural ethnographic case studies.