"Rational Animals: The Teleological Roots of Intentionality" offers an original account of the intentionality of human mental states, such as beliefs and desires. The account of intentionality in "Rational Animals" is broadly biological in its basis, emphasizing the continuity between human intentionality and the levels of intentionality that should be attributed to animal actions and states. Establishing the goal-directed character of animal behavior, Mark Okrent argues that instrumentally rational action is a species of goal-directed behavior that is idiosyncratic to individual agents and is distinguished by its novelty and flexibility. He also argues that some nonlinguistic animals are capable of instrumental rationality and that in the first instance, the contents of beliefs and desires are individuated by the explanatory role of those states in rationally accounting for such instrumentally rational behavior. The account of instrumental rationality offered in Rational Animals allows for understanding the practical rationality of linguistically competent human beings as a distinctive capacity of social animals capable of undertaking roles governed by socially sanctioned norms. Rational Animals will be of interest to cognitive scientists, philosophers of mind, philosophers of biology, philosophers of action, ethologists, and those interested in the debates concerning animal intelligence.