I propose a fitting attitude account of moral wrongness.  Such an account requires two components: first, an account of the attitude in terms of which moral wrongness is to be understood, and, second, an account of the fittingness conditions of this attitude.  I argue that moral wrongness is to be understood in terms of a sui generis attitude of moral norm acceptance.  In particular, I argue that an action is wrong if and only if it would be fitting to have an attitude of moral norm acceptance toward a norm that prohibits this action.  Then, after sketching an account of the functional role of the attitude of moral norm acceptance, I offer a naturalistic account of the fittingness conditions for this attitude, which follows from a more general naturalistic conception of the nature of fittingness. The result is a naturalistic picture of moral wrongness.