In order for us to understand what public policy might actually help improve cities with a large homeless population, then we need to understand what assumptions public policy makers might have about the homeless which work against public interest.
It is assumed that the majority of homeless become so because of addiction issues or mental illness. First, that assumes that the majority of the homeless are the chronic homeless (the most obvious homeless population), instead of the majority homeless—families who are experiencing economic hardship and will be housed again in just a few months.
Recent data has shown that only a minority of the homeless end up on the street due to addiction issues (14 percent) or mental illness. The main causes of homelessness would be: loss of job, or being kicked out of one’s apartment or house. There is greater indication that obvious mental illness and addiction is widespread among the chronic homeless as a result of the extreme stresses of living on the street.
(National Coalition for the Homeless http://www.nationalhomeless.org/factsheets/why.html )