The proposal that the criminal justice system should focus on rehabilitation—rather than retribution, deterrence, or expressive denunciation—is among the least popular ideas in legal philosophy. Foremost among rehabilitation’s alleged weaknesses is that it treats criminals like blameless patients to be treated, rather than culpable moral agents to be held accountable. This article offers a new interpretation of the rehabilitative approach that is immune to this objection and that furnishes the moral foundation that this approach has lacked. The view rests on the principle that moral agents owe it to one another to maintain the dependability of their moral capacities. Agents who culpably commit criminal wrongs, however, betray an unacceptable degree of moral unreliability. Punishment, on this theory, consists in the enforcement of the duties that offenders have to reduce their own likelihood of recidivism.