This volume brings together specially written essays by leading researchers on the propositional imagination. This is the mental capacity we exploit when we imagine that Holmes has a bad habit or that there are zombies. The propositional imagination---the mental capacity we exploit when we imagine that everyone is colour-blind or that Hamlet is a procrastinator---plays an essential role in philosophical theorizing, engaging with fiction, and indeed in everyday life. These thirteen essays, specially written for the volume, capitalize on this recent work, extending the theoretical picture of the imagination and exploring the philosophical implications of cognitive accounts of the imagination.