Conditioning can produce desires that seem to be outside of--or “alien” to--the agent. Desire-based theories of welfare claim that the satisfaction of desires creates prudential value. But the satisfaction of alien desires does not seem to create prudential value. To explain this fact, we need an account of alien desires that explains their moral status. In this paper I suggest that alien desires are desires that would be rational if the person believed something that in fact she believes is false. Such desires could be produced by mental representations--or “quasi-beliefs”--with contents that conflict with the contents of one’s beliefs. The postulation of quasi-beliefs is plausible, for they explain important empirical facts about our behavior--facts that are difficult if not impossible to explain otherwise. Alien desires, I argue, involve quasi-beliefs with contents that conflict with the contents of regular beliefs. This theory provides the distinction between alien and authentic desires that desire-based theories of welfare need