I argue that Spinoza endorses "conceptual dependence monism," the thesis that all forms of metaphysical dependence (such as causation, inherence, and existential dependence) are conceptual in kind. In the course of explaining the view, I further argue that it is actually presupposed in the proof for his more famed substance monism. Conceptual dependence monism also illuminates several of Spinoza’s most striking metaphysical views, including the intensionality of causal contexts, parallelism, metaphysical perfection, and explanatory rationalism. I also argue that this priority (...) of the conceptual does not commit Spinoza to forms of idealism or mentalism. The question of how to understand different kinds of metaphysical dependence is quite controversial in Spinoza studies; I address major alternative readings in the notes. But there I also try to draw connections to the growing debate in contemporary discussions about metaphysical dependence, as this topic is a happy point of shared interest between Spinoza and contemporary metaphysicians alike. (shrink)