 Different accounts of scientific reduction have shaped debates about diverse topics including scientific unification, the relation between (folk-)psychology and neuroscience, the metaphysics of the mind, the status of biology vis à vis chemistry, and the relation between allegedly teleological explanations and causal explanations. Understanding the relevant notions is thus a prerequisite for understanding key issues in contemporary analytic philosophy. Moreover, the notion of reduction itself has become a target of recent philosophical discussion, especially in the philosophy of science and in metaphysics.