The long-term goal of this study is to determine, in homeless adults aged 50 and over, the key life events and precipitants of homelessness and how these are associated with the prevalence, severity, trajectory and consequences of geriatric conditions in order to guide prevention, healthcare, social service and housing interventions. The average age of homeless adults in the United States has risen dramatically in the last 20 years;while only 11% of the homeless population was age 50 and older in 1990, half is now. Little is known about the life trajectories that lead to late-life homelessness or the role of agin-related conditions in poor outcomes. Policies and programs directed at preventing and ameliorating homelessness were designed before the age distribution changed and do not address aging issues. Homeless adults experience premature aging and are not able to make compensatory changes in their environment, suggesting that geriatric conditions may be a substantial factor in poor outcomes. Little is known about the characteristics or consequences of geriatric conditions in this population;these data are needed to design and implement effective policies and programs. The proposed study will address this gap by assembling and following a cohort of 350 homeless adults age 50 and older in order to address the following aims: 1) To identify key life events and precipitants of homelessness 2) To determine the prevalence, severity and trajectory of geriatric conditions and their association with life course events and 3 To examine predictors (including life course events and geriatric conditions) of acute health care utilization (Emergency Department visits and hospitalizations). Participants will be recruited from emergency shelters, subsidized food programs, and homeless encampments in Oakland, CA using a multi- stage probability sampling design. Participants will be followed for 3 years, with a baseline study visit and 6 semi-annual follow-up visits for structured interviews. Subsamples will undergo in-depth interviews to explore key events and precipitants. Study visits will take place at St. Mary's Center, a multiservice community-based center for older homeless adults. Trained research assistants, working under the close supervision of the study investigators and a neuropsychologist, will administer clinical assessments and structured interviews using validated instruments to assess life course events preceding homelessness, geriatric conditions (functional and cognitive impairments), behavioral health (mental health and alcohol and illicit substance use), physical health (chronic diseases), and acute healthcare utilization (Emergency Department visits, inpatient hospitalizations). We will gather mortality data through death record registries. An Advisory Board of community and policy leaders with extensive expertise with homeless programs and policies will work with the study team to guide study development and help translate the findings into practice and policy changes. Study findings will ultimately contribute to the development of clinical, programmatic and policy recommendations to prevent and ameliorate the effects of homelessness among older adults.