Designers of mobile, social systems must carefully think about how to help their users manage spatial, semantic, and social modes of navigation. Here, we describe our deployment of MobiTags, a system to help museum visitors interact with a collection of “open storage” exhibits, those where the museum provides little curatorial information. MobiTags integrates social tagging, art information, and a map to support navigation and collaborative curation of these open storage collections. We studied 23 people’s use of MobiTags in a local museum, combining interview data with device use logs and tracking of people’s movements to understand how MobiTags affected their navigation and experience in the museum. Despite a lack of social cues, people feel a strong sense of social presence—and social pressure—through seeing others’ tags. The tight coupling of tags, item information, and map features also supported a rich set of practices around these modes of navigation. Author Keywo...