Paragraphs 381-404 of Theodicy contain one of the most systematic discussions of the action of creatures ever provided by Leibniz. Although they expressly reject Bayle’s view that creatures are not truly efficient causes of their states, they also have a wider target, namely the ‘new Cartesian’ tenets such as the continuous creation doctrine. A close scrutiny of these paragraphs casts new light on two main issues in Leibniz’s defence of the active power of creatures: first, the relation between the substances and their accidents; second, the consistency of Leibniz’s view with the traditional theological doctrine of God’s concurrence. Leibniz’s solution of these difficulties is philosophically interesting, for it offers both a very refined version of a traditional ‘endurantist’ view on individual persistence and a robust metaphysics of dispositions and dispositional properties. This metaphysics is also the ground of Leibniz’s final doctrine of the relations Nature/Miracle and Nature/Grace.