Abstract The thesis that teleological explanations are best understood as causal explanations is defended (contra Valentine). I shift the focus of debate from behavior simpliciter to allegedly rational behavior. Teleological explanation, in the case of rational agents, involves reason?giving; and the reasons agents give for acting must be causative of that action if those agents are to be rational in practice. I argue initially that to abandon the claim that reasons are causes of action is to abandon that which renders (...) many generalisations of systematic human behavior intelligible. I then adduce and defend against two major objections to the secondary thesis that reasons can be causes of action: (1) Experiments in attribution research suggest that agents are characteristically mistaken when reporting on the causes of their behavior; (2) Causal explanation must refer to some law, and reasons cannot enter into such laws as causes of action. In responding to these objections, I note that strict predictability is probably not a reliable indicator of genuine causal explanation; some explanations will afford predictions, others will not. (shrink)