According to the standard view of his metaphysics, Leibniz endorses idealism: the thesis that the world is made up solely of minds or monads and their perceptual and appetitive states. Recently,this view has been challenged by some scholars, who argue that Leibniz can be seen as admitting corporeal substances, that is, animals or embodied souls, into his ontology, and that, therefore, it is false to attribute a strict idealism to him. Subtler accounts suggest that Leibniz begins his philosophical career as (...) an advocate of (some form of) the modern ‘mechanical’ philosophy and ends his career as an idealist, raising the issue when and why Leibniz adopts his monadological metaphysics. This article argues that, given a constellation of metaphysical, logical, and theological views, Leibniz is committed to the ontological primacy of mind or form even in his ‘middle years’. (shrink)