California Public Policy and Citizen Participation/Homeless Vulnerability Index
The Vulnerability Index, as used with respect to homeless issues, is a survey and analysis methodology for "identifying and prioritizing the street homeless population for housing according to the fragility of their health." It is a pragmatic methodology based on concern and inquiry into the reasons for recurring fatalities of homeless living in the outdoor urban context. It was developed by Dr. Jim O'Connell of Boston’s Healthcare for the Homeless organization.
According to its proponents, his work succeeded in pinpointing the health problems that led to homeless persons being "most at risk for dying on the street". He lists eight conditions, in medical terminology called "markers". According to Common Ground, a national organization to house the homeless, 40% of the Boston mortality was attributable to those factors.
In its formulation as currently promulgated by Common Ground, the index includes these factors: hospitalizations/emergency room visits in a year, age, HIV-AIDS, liver disease or kidney disease, history of frostbite, immersion foot, or hypothermia, and tri-morbidity. Tri-morbidity is co-occurring disorder (psychiatric, substance abuse) with a chronic medical condition.
A national drive is underway by Common Ground to piggy back data collection for the VI onto the bi-annual homeless enumeration count mandated for communities participating in the Continuum of Care grant program of the US Department of Housing and Urban Development. Its proponents contend that such demand side data will assist in placements and getting needy individuals off the street, whereas critics argue that it is intrusive and not likely to lead to increased supply of housing.
The Vulnerability Index has been used outside of the north eastern United States. Cities include Charlotte, North Carolina, Albuquerque,New Mexico, Santa Monica, California. Los Angeles, California, Santa Barbara, California|Santa Barbara, California and New Orleans, Louisiana.By June of 2011, it had also been deployed in various cities in Australia.
Antecedent use of the concept
A vulnerability index for the environmental concerns was developed by the South Pacific Applied Geoscience Commission (SOPAC) with the United Nations Environment Programme (UNEP). They noted that the concept of vulnerability could be applied at to various "levels or issues." They specifically noted that it could be applied to "a single issue... or to assess a complex entity such as a country." In sociological research, a distinction is made between indexes and scales. The former often weights variables equally but in any case does not register patterns of data. A scale on the other hand presents a structure in which certain patterns of the variables tend to aggregate at one end of the scale and go together in ascending order.
Papers associated with Small independent developing societies research used the term "vulnerability index" long before its adoption by Dr. O'Connor. United Nations – DPCSD (1997). This took two forms; the term was used in combination with a qualifier. Examples are "environmental vulnerability index" and "Economic Vulnerability Index". However, the raw term "Vulnerability Index" appeared in an epinonymous background paper cited by Professor Lino Briguglio, University of Malta, an expert on "the development of indices for measuring the economic and environmental vulnerability of small island developing states". 
- A Brief Preview of Registry Week
- Common Ground Au Cited in Vulnerability index on English Wikipedia
- Vulnerability Index (Revised Background Paper). SD-SIDS Unit.