This book investigates the nature of reality from the viewpoint of a physicist. Contemporary physics, especially quantum theory, has raised profound questions about the relationship between the methods of science and the reality these methods seek to investigate. These questions, and how we should answer them, are the subject of this book. Part I examines the practices of contemporary physicists and addresses the criticisms that philosophers of science have made of these practices. The doctrine of physical realism, adopted by most physicists and many philosophers of science, is subjected to detailed investigation in Part II. When tested against recent discoveries and developments in physics, it is shown to be in considerable difficulty. Part III explores the consequences of this for our understanding of what science can seek to know of reality, and concludes by outlining the position contemporary physics indicates we should take on the nature of reality generally considered.