Despite increasing popularity of stereo capture and display systems, creating stereo artwork remains a challenge. This paper presents a stereo painting system, which enables effective from-scratch creation of high-quality stereo artwork. A key concept of our system is a stereo layer, which is composed of two RGBAd (RGBA + depth) buffers. Stereo layers alleviate the need for fully formed representational 3D geometry required by most existing 3D painting systems, and allow for simple, essential depth specification. RGBAd buffers also provide scalability for complex scenes by minimizing the dependency of stereo painting updates on the scene complexity. For interaction with stereo layers, we present stereo paint and stereo depth brushes, which manipulate the photometric (RGBA) and depth buffers of a stereo layer, respectively. In our system, painting and depth manipulation operations can be performed in arbitrary order with real-time visual feedback, providing a flexible WYSIWYG workflow for stereo painting. Our data structures allow for easy interoperability with existing image and geometry data, enabling a number of applications beyond from-scratch art creation, such as stereo conversion of monoscopic artwork and mixed-media art. Comments from artists and experimental results demonstrate that our system effectively aides in the creation of compelling stereo paintings.