Perspective-taking has been one of the central concerns of work on social attention and developmental psychology for the past 60 years. Despite its prominence, there is no formal description of what it means to represent another’s viewpoint. The present article argues that such a description is now required in the form of theory—a theory that should address a number of issues that are central to the notion of assuming another’s viewpoint. After suggesting that the mental imagery debate provides a good framework for understanding some of the issues and problems surrounding perspective-taking, we set out nine points that we believe any theory of perspective-taking should consider.