In , Jill North addresses a set of questions that get to the heart of the project of interpreting physics—of figuring out what physics is telling us about the world. How do we figure out the nature of the world from a mathematically formulated physical theory? What do we infer about the world when a physical theory can be mathematically formulated in different ways? North argues that there is a certain notion of structure, implicit in physics and mathematics, to which we should pay careful attention in order to discern what physics is telling us about the nature of reality. North draws lessons for related topics, including the use of coordinate systems in physics, the differences among various formulations of classical mechanics, the nature of spacetime structure, the equivalence of physical theories, and the importance of scientific explanation. Although the book does not explicitly defend scientific realism, instead taking this to be a background assumption, the account provides an indirect case for realism toward our best theories of physics.