Based on two years of fieldwork, conducted between March 2003 and March 2005 in the health care industry of the northeastern United States, this study shows that the work of family caregivers of elders goes far beyond previously recognized care in the home to acknowledge care inside health care facilities and in conjunction with community services. It reveals that family caregivers — untrained, undersupported, and unseen — constitute a “shadow workforce,” acting as geriatric case managers, medical record keepers, paramedics, and patient advocates to fill dangerous gaps in a system that is uncoordinated, fragmented, bureaucratic, and often depersonalized. Detailed examination of what family caregivers actually do in traversing multiple domains reveals the extent of their contribution to and the weaknesses in the present geriatric health care system. It suggests that the experiences of family caregivers must be central to the creation of new policies and a more coordinated system that uses the complex work of family caregivers by providing the training and support that they need.