Social anthropologists mostly study kinship as a principle of social organisation. But there is also a psychological and cognitive side to human kinship, involving questions like: How do people recognise others as kin of one sort or another? What do kin categories mean and how are they related to one another? What, if anything, distinguishes thinking about kinship from other varieties of social cognition? Different schools of anthropology offer very different answers to these questions. Here I review three approaches to the psychology of kinship. One has its roots in evolutionary theory and human/nonhuman comparisons. The second is concerned with symbolism, culture, and the natives' explicit theories of procreation and kinship. These approaches are likely to be familiar to students of evolution and human behaviour, and cultural anthropology, respectively. The third approach stems from recent developments in cognitive science, especially in the study of specialised domains of cognition. This approach is newest, and probably least familiar to most anthropologists and even to most cognitive scientists, so it receives most attention here. I argue that human beings have a specialised cognitive system-which can be called 'kinship core cognition' or 'kinship conceptual structure'-comprising a set of universal building blocks for organising knowledge of kin and kin categories in an abstract kinship space. Much of the success of formal methods in the study of kin