Teaching has long been a neglected area in animal behaviour, despite its relevance for a wide range of topics. In light of recent evidence for teaching in nonhuman animals, research can begin to examine the conditions under which it may evolve. Here, we make the case for an evolutionary perspective that treats teaching as a form of cooperative behaviour which functions to promote learning in others. We outline its key characteristics and discuss the selection pressures that may favour its evolution. Teaching will be favoured by selection only where the costs to teachers of facilitating learning are outweighed by the long-term fitness benefits they accrue once pupils have learned, and these benefits will be scaled by the ease with which pupils could learn without teaching. This perspective allows us to make predictions as to the distribution of teaching, the forms it may take, and the relation between teaching in humans and other species.We conclude by considering how teaching may best be categorized.We suggest that natural selection is likely to favour different forms of teaching, depending on whether it serves to promote learning of procedural or declarative information. Keywords: cooperation, culture, evolution, parental care, social learning, teaching-