Recent philosophy of mind has had a mistaken conception of the nature of psychological concepts. It has assumed too much similarity between psychological judgments and those of natural science and has thus overlooked the fact that other people are not just objects whose thoughts we may try to predict and control but fellow creatures with whom we talk and co-operate. In this collection of essays, Jane Heal argues that central to our ability to arrive at views about others' thoughts is not knowledge of some theory of the mind but rather an ability to imagine alternative worlds and how things appear from another person's point of view. She then applies this view to questions of how we represent others' thoughts, the shape of psychological concepts, the nature of rationality and the possibility of first person authority. This book should appeal to students and professionals in philosophy of mind and language.