Nurses at the Well-Being Institute, a community-based nursing outreach clinic in Detroit, Michigan, located 75 women living with HIV, mental illness, and substance abuse who were lost to follow-up at their HIV medical clinic as part of a nursing research study. Women who had been scheduled for an appointment in the last 4 months but who had missed that appointment were considered "lost to follow-up" in the HIV clinic. The purpose of the research was to study factors related to health care access in women not participating in regular health care for their HIV infection. Women were randomly assigned to two study groups. Women assigned to "care as usual" study group (n = 37) received no additional services beyond study interviews for 1 year. Women assigned to the "nursing intervention" group (n = 38) were provided with nursing services designed to facilitate their return to and continued connection with their HIV clinic. Findings showed that factors related to the women's vulnerability, such as mental illness and drug use, were more related to their use of expensive health care services such as hospital emergency departments or hospital inpatient admissions than was assignment to either the "nursing intervention" or "care as usual" study groups. Two case studies describing the cost of care for 2 of the multiply diagnosed women in the study is presented. The women differed on whether they had stable housing and were accessing care for their mental illness.