I develop a Latin Social model of the Trinity that is an extension of my previous article on indexicals and the Trinity. I focus on the theological desideratum of the necessity of the divine persons’ unity of action. After giving my account of this, I compare it with Swinburne’s and Hasker’s social models and Leftow’s non-social model. I argue that their accounts of the divine persons’ unity of action are theologically unsatisfactory and that this unsatisfactoriness derives from a modern conception (...) of personhood according to which distinct and incommunicable intellectual acts and volitional acts are necessary conditions for one’s being a person. I argue that the Latin Social model is preferable to the modern-personhood models because it is simpler in explanatory economy with regard to securing the necessity of the divine persons’ unity of action. (shrink)