Malebranche famously subscribes to the doctrine of occasionalism, according to which God is the only genuinely causally active being. This chapter introduces the basic building blocks of George Berkeley’s metaphysics. It considers what the relata of the causal relation are for Berkeley and explains why there is often thought to be pressure on Berkeley to join Malebranche in denying creaturely causation altogether. The chapter deals with the question whether, according to Berkeley, causes necessitate their effects, and argues, contrary to what some commentators have recently claimed, that it is very difficult to settle this issue conclusively. It also introduces the so-called Transparency Thesis, which is the claim that ideas contain nothing that remains unperceived, to which Berkeley commits himself. Berkeley’s ontology has quite appropriately been characterized as dualist. For Berkeley, there are only two types of created beings: perceived things and perceivers.