Housing first or treatment first?

In the Bay Area one of the big unanswered questions concerning homelessness is: housing first, or treatment first? Housing-first adherents argue that the first thing to do with homeless people is to get them into permanent housing. This, they claim, is because a lack of housing is responsible for all of their other problems (drug addiction, mental illness, criminal behavior, etc.) and it makes no sense to treat symptoms without getting to their root cause—the absence of a place to live.