Roughly, psychological egoism is the thesis that all of a person's intentional actions are ultimately self-interested in some sense; psychological altruism is the thesis that some people's intentional actions are ultimately other-regarding in some sense. C. Daniel Batson and other social psychologists have argued that there are experiments that provide support for a theory called the 'empathy-altruism hypothesis', which entails the falsity of psychological egoism. However, several critics claim that there are egoistic explanations of the data that are still not ruled out. One of the most potent criticisms of Batson comes from Elliott Sober and David Sloan Wilson. I argue for two main theses in this paper: (1) we can improve on Sober and Wilson's conception of psychological egoism and altruism, and (2) this improvement shows that one of the strongest of Sober andWilson's purportedly egoistic explanations is not tenable. A defense of these two theses goes some way toward defending Batson's claim that the evidence from social psychology provides sufficient reason to reject psychological egoism. © 2009 Blackwell Publishing Ltd.