Introduction: modern philosophies of punishment and the return to Aquinas -- The problem with the utilitarian theory of punishment -- The problem with modern retributivism -- Foundations of the Thomistic theory of punishment -- The moral basis of punishment: Aquinas's retributivism -- Beyond retribution: punishing criminals in civil society -- Capital punishment, evangelium vitae, and the Thomistic theory of punishment -- Conclusion: Thomas Aquinas and modern theories of punishment