The creation of multimodal user interfaces, blending GUI and VUI, presents unique challenges. Graphical and voice interaction designers have a wide experience in crafting user interfaces in their respective areas, but relatively little work has been done combining the two. What guidelines and heuristics from VUI design carry over to designing multimodal user interfaces? And what VUI guidelines don’t transfer well to multimodal user interfaces? What GUI and multimodal user interface (MUI) guidelines should voice designers be aware of? Join this discussion about new frontiers in the design of devices and applications.