Emergency departments (EDs) frequently care for patients who are homeless or unstably housed. One promising approach taken by the homeless services system is to provide interventions that attempt to prevent homelessness before it occurs. Experts have suggested that health care settings may be ideal locations to identify and intervene with patients at risk for homelessness, yet little is known even about the basic characteristics of patients who might benefit from such interventions. This qualitative study examines themes that may lead to homelessness.