In this article I dispute the claim, made by several contemporary scholars, that Spinoza was a naturalist. ‘Naturalism’ here refers to two distinct but related positions in contemporary philosophy. The first, ontological naturalism, is the view that everything that exists possesses a certain character permitting it to be defined as natural and prohibiting it from being defined as supernatural. I argue that the only definition of ontological naturalism that could be legitimately applied to Spinoza's philosophy is so unrestrictive as to (...) tell us nothing about the content of his ideas. The second, methodological naturalism, is the view that the natural sciences are the best means of finding out substantial truths about the concrete world. I present some historical research showing that Spinoza's way of positioning himself with respect to other philosophers in the Dutch Republic casts very serious doubt on the claim that he was a methodological naturalist. This adds further weight to arguments that have already been made against the naturalist reading of Spinoza. (shrink)