||An interdisciplimary research group at Carnegie Mellon University (CMU) is investigating the design and usefulness of mobile CSCW systems for the support of distributed diagnosis, repair, and redesign of large vehicles, such as aircraft and trains. These systems incorporate diagnostic aids, on-line maintenance manuals, schematic drawings, and telecommunications that allow workers to access both stored information and interactive help from remote experts. This videotape illustrates the problem area and some wearable computer prototypes. It describes some of the field work we have done documenting the value of collaboration when workers are diagnosing and repairing complex equipment. Our laboratory experiments investigate whether wireless video capabilities are useful. One prototype incorporates both shared computer-based information (an on-line repair manual) and a shared view of the non-computerized work space (a video feed from a head-mounted camera). Experiments so far show that commumication with a remote expert improves the speed and quality of repairs, but that shared video does not. Video does, however, affect how collaborators coordinate their behavior, for example by allowing a pair to be less verbally explicit. The videotape illustrates how a collaborative pair can exploit both shared data sources to communicate more effectively.