A Materialist Theory of Mind (1968) by David Armstrong is one of a handful of texts that began the physicalist revolution in the philosophy of mind. It is perhaps the most influential book in the field of the second half of the twentieth century. In this volume a distinguished international team of philosophers examine what we still owe to Armstrong’s theory, and how to expand it, as well as looking back on how it came about. The first four chapters are historical in orientation, exploring how the book fits into the history of materialism in the twentieth century. The chapters that follow discuss perception, belief, the supposed explanatory gap between the physical and the mental, introspection, conation, causality, and functionalism.