In the nearly 30 years since Premack and Woodruff famously asked, “Does the chimpanzee have a theory of mind?”, the question of exactly how much non-human primates understand about the mental lives of others has had an unusually dramatic history. As little as ten years ago it appeared that the answer would be a simple one, with early investigations of non-human primates’ mentalistic abilities yielding a steady stream of negative findings. Indeed, by the mid-1990s even very cautious researchers were ready to flatly assert that Theory of Mind was a uniquely human capacity. Recently, however, an exciting new theoretical perspective on primate social cognition has arisen, and with it the distinct possibility that our evolutionary relatives may understand far more of the social world than we previously believed. In this paper we review new theory and evidence suggesting that non-human primates may indeed represent the mental states of others, at least within the domains for which their distinctive social ecology has prepared them. Having asserted that Premack and Woodruff's original question can be answered with a qualified yes, we then consider the new questions that arise in its place, particularly how and why our own Theory of Mind became more domain-general than that of other primates.