It is often claimed that humans are rational, linguistic, cultural, or moral creatures. What these characterizations may all have in common is the more fundamental claim that humans are normative animals, in the sense that they are creatures whose lives are structured at a fundamental level by their relationships to norms. The various capacities singled out by discussion of rational, linguistic, cultural, or moral animals might then all essentially involve an orientation to obligations, permissions and prohibitions. And, if this is so, then perhaps it is a basic susceptibility, or proclivity to normative or deontic regulation of thought and behavior that enables humans to develop the various specific features of their life form. This volume of new essays investigates the claim that humans are essentially normative animals in this sense. The contributors do so by looking at the nature and relations of three types of norms, or putative norms-social, moral, and linguistic-and asking whether they might all be different expressions of one basic structure unique to humankind. These questions are posed by philosophers, primatologists, behavioral biologists, psychologists, linguists, and cultural anthropologists, who have collaborated on this topic for many years. The contributors are committed to the idea that understanding normativity is a two-way process, involving a close interaction between conceptual clarification and empirical research.