Many ethicists writing about well-being have assumed that claims made about the relationship between pleasure and well-being carry similar implications for the relationship between pain and well-being. I argue that the current neuroscience of pleasure and pain does not support this assumption. In particular, I argue that the experiences of pleasure and pain are mediated by different cognitive systems, that they make different contributions to human behavior in general and to well-being in particular, and that they bear fundamentally different relationships (...) to our motivational systems and hence desires. I further argue that though there is ample evidence that pleasure can be dissociated from appetitive motivation, there is no compelling evidence suggesting that the unpleasantness of pain can be dissociated from the aversive motivational force of pains. I consider several objections to this claim, including Jennifer Corns’ recent arguments that the unpleasantness of pain experience can be dissociated from the motivational signal of pain, before briefly drawing some lessons for ethics. (shrink)