Some sacrifices—like giving a kidney or heroically dashing into a burning building—are supererogatory: they are good deeds beyond the call of duty. But if such deeds are really so good, philosophers ask, why shouldn’t morality just require them? The standard answer is that morality recognizes a special role for the pursuit of self-interest, so that everyone may treat themselves as if they were uniquely important. This idea, however, cannot be reconciled with the compelling picture of morality as impartial—the view that we are each anyone’s equal. I propose an alternative Self-Other Symmetric account of our moral freedom: the limits on what morality may demand of us are set by the duties we owe to ourselves. I begin with a defense of the Sel...