 Spinoza was aware of how deeply against the grain of common sense the truth of necessitarianism would run. If he nonetheless believed in its truth, he must have thought he had very compelling reasons for doing so. What might such reasons be? We will begin with substance necessitarianism (2.1) and then turn to the necessity of modes (2.2). Although the case for interpreting Spinoza as a mode necessitarian is strong, there are also Spinoza-friendly reasons for resisting such a reading. Seeing this tension will lead us into the middle of an interpretive controversy that has ramifications for understanding many of Spinoza’s other central metaphysical views. (In section 2, we will undercover one possible way of reconciling Spinoza’s drive towards necessitarianism with what might have been equally important reasons for avoiding it.)