Collage Diffusion is a novel interface for interacting with image generation models. It allows you to specify the composition of an image in a familiar Photoshop-like interface. Our modified version of Stable Diffusion takes the layers in and produces a harmonized image, ensuring that everything from perspectives to lighting are plausible. Unlike text prompting supported by traditional diffusion interfaces, Layered Diffusion allows you to precisely outline how a scene should be composed—from where objects are relative to each other to what they look like.