In this paper, I argue that Spinoza's claim at E1P15 that “Whatever is, is in God, and nothing can be or be conceived without God” remains exegetically troubling. Briefly noting some unresolved difficulties with the two dominant interpretations of Spinoza's account of the relationship between finite modes and God (these being the inherence and causal dependence readings), I move to claim that there is a third, neglected reading available which deserves consideration. I argue that, perhaps surprisingly, Althusser's notion of “structural (...) causality,” putatively derived from Spinoza himself, can be used to construct this reading. Althusser's original notion of “structural causality” is explained and clarified further, its advantages outlined over competing readings of Spinoza, and exegetical evidence for its applicability to Spinoza is then produced. (shrink)