We describe a prototype system that combines together the overlaid 3D graphics of augmented reality with the untethered freedom of mobile computing. The goal is to explore how these two technologies might together make possible wearable computer systems that can support users in their everyday interactions with the world. We introduce an application that presents information about our university’s campus, using a head-tracked, see-through, headworn, 3D display, and an untracked, opaque, handheld, 2D display with stylus and trackpad. We provide an illustrated explanation of how our prototype is used, and describe our rationale behind designing its software infrastructure and selecting the hardware on which it runs.