1. Introduction; 2. Metaphysical foundations; 3. Evil as privation; 4. Aquinas' account of moral wrongdoing: general point and defects in the intellect; 5. Aquinas' account of moral wrongdoing: defects in the sensory appetite; 6. Aquinas' account of moral wrongdoing: defects in the will; 7. The vices in Aquinas' moral psychology.