Process philosophers and theologians have long been critical of the traditional (Thomist) doctrine of divine immutability (Section I); yet until quite recently their protests had been largely ignored in Roman Catholic circles. The purpose of this present article is to draw attention to the fact that a number of contemporary Roman Catholic theologians have begun to take the Whiteheadian-Hartshornean challenge seriously, indeed to the extent that they have felt pressed, in response, to seek and exploit implicit, latent resources within Thomas' texts in order to explicate a more adequate Thomist conception of God's interrelationship with his creatures (Section II). Process metaphysics is defended versus several criticisms raised by Roman Catholic writers (Section III).