Culture in humans connotes tradition, norms, ritual, technology, and social learning, but also cultural events like operas or gallery openings. Culture is in part about what we do, but also sometimes about what we ought to do. Human culture is inextricably intertwined with language and much of what we learn and transmit to others comes through written or spoken language. Given the complexities of human culture, it might seem that we are the only species that exhibits culture. How, then, are we to make sense of culture in animals? The study of animal culture is a booming research area. Culture is said to occur in a wide range of vertebrates from our close kin, chimpanzees (Whiten et al. 1999) and orangutans (van Schaik et al. 2003), to more distant relatives like rats (Galef and Aleen 1995) and whales (Whitehead and Rendell 2015). Could these studies be misleading in that they are not actually studying culture but simply misapplying the term ‘culture’? Or is what is labeled culture in animals at the core of human culture, so that although human culture is more elaborate than animal culture, it is different in degree, not kind? While it is certainly easy to intentionally define culture in a way that makes it unique to humans, because of the growing field of animal culture, it would be most useful to attempt to offer a definition of culture that makes sense of how it is used by psychologists, biologists, anthropologists, and others who use the term culture in studies of animal behavior. The challenge is to produce a concept that is broad enough to be able to apply across humans and animals, but not be so anemic that it cannot do justice to human culture. Because of this, I will here construct a definition of animal culture and draw out some of its implications.